$140+ Cheap flights from Seattle (SEA) to Illinois
This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 7/8. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Jul 6 — Jul 131
Round-trip
1 adult, Economy
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Find cheap flights from Seattle to Illinois with Cheapflights
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Cheapest flights from Seattle to IllinoisExplore the most affordable flight options available from Seattle to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 6, 2026.
Explore the most affordable flight options available from Seattle to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 6, 2026.
This American Airlines deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/176:23 am
SEA
- BMI
1 stop7h 23m
American Airlines
Sat 10/246:39 pm
BMI
- SEA
1 stop7h 35m
American Airlines
Deal found 6/2![American Airlines logo]()
$343
This CheapOair deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/111:03 am
SEA
- ORD
1 stop17h 16m
Frontier
Sun 9/69:07 pm
ORD
- SEA
1 stop23h 19m
Frontier
Deal found 6/5![Frontier logo]()
$344
This Expedia deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/810:31 am
SEA
- ORD
Nonstop4h 17m
Multiple Airlines
Tue 6/99:48 pm
ORD
- SEA
1 stop18h 30m
Multiple Airlines
Deal found 6/5![Multiple Airlines logo]()
$345
This CheapOair deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/247:41 pm
SEA
- ORD
1 stop23h 02m
Frontier
Sun 6/287:20 am
ORD
- SEA
1 stop29h 15m
Frontier
Deal found 6/6![Frontier logo]()
$346
This Southwest deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/2511:05 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Sun 9/275:35 pm
MDW
- SEA
2 stops9h 15m
Southwest
Deal found 6/5![Southwest logo]()
$346
This American Airlines deal was found by Cheapflights users on 6/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/135:00 am
SEA
- BMI
1 stop9h 19m
American Airlines
Sat 8/155:40 pm
BMI
- SEA
1 stop8h 33m
American Airlines
Deal found 6/4![American Airlines logo]()
$346
This Booking.com deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/195:48 pm
SEA
- ORD
Nonstop4h 11m
Multiple Airlines
Sat 6/209:48 pm
ORD
- SEA
1 stop14h 00m
Multiple Airlines
Deal found 6/6![Multiple Airlines logo]()
$347
This Southwest deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/16:40 am
SEA
- MDW
2 stops7h 20m
Southwest
Sun 9/68:25 am
MDW
- SEA
1 stop6h 35m
Southwest
Deal found 6/5![Southwest logo]()
$347
This Expedia deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/912:45 pm
SEA
- ORD
Nonstop4h 18m
Multiple Airlines
Thu 6/117:20 am
ORD
- SEA
1 stop29h 15m
Multiple Airlines
Deal found 6/5![Multiple Airlines logo]()
$348
This CheapOair deal was found by Cheapflights users on 6/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/43:19 pm
SEA
- ORD
1 stop27h 34m
Frontier
Mon 9/79:48 pm
ORD
- SEA
1 stop14h 00m
Frontier
Deal found 6/4![Frontier logo]()
$349
This Southwest deal was found by Cheapflights users on 6/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/285:00 am
SEA
- MDW
Nonstop3h 55m
Southwest
Tue 8/46:00 am
MDW
- SEA
1 stop7h 15m
Southwest
Deal found 6/3![Southwest logo]()
$349
This Delta deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/310:58 pm
SEA
- MLI
1 stop9h 26m
Delta
Mon 8/105:09 pm
MLI
- SEA
1 stop8h 48m
Delta
Deal found 6/2![Delta logo]()
$349
Best flights from Seattle to IllinoisDiscover carefully curated flight deals from Seattle to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated June 6, 2026.
Discover carefully curated flight deals from Seattle to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated June 6, 2026.
This American Airlines deal was found by Cheapflights users on 6/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/145:05 am
SEA
- MLI
1 stop9h 06m
American Airlines
Sat 7/186:50 pm
MLI
- SEA
1 stop8h 02m
American Airlines
Deal found 6/1![American Airlines logo]()
$349
This Alaska Airlines deal was found by Cheapflights users on 6/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/1611:29 am
SEA
- ORD
Nonstop4h 09m
Alaska Airlines
Thu 7/166:42 pm
ORD
- SEA
Nonstop4h 52m
Alaska Airlines
Deal found 6/1![Alaska Airlines logo]()
$350
This Delta deal was found by Cheapflights users on 6/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/75:40 pm
SEA
- ORD
Nonstop3h 58m
Delta
Tue 7/145:55 pm
ORD
- SEA
Nonstop4h 39m
Delta
Deal found 6/1![Delta logo]()
$355
This Kiwi.com deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/99:16 pm
SEA
- RFD
1 stop21h 23m
Multiple Airlines
Sun 9/139:29 pm
RFD
- SEA
2 stops14h 22m
Multiple Airlines
Deal found 6/5![Multiple Airlines logo]()
$360
This Southwest deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/15:00 am
SEA
- MDW
Nonstop3h 55m
Southwest
Mon 10/56:30 am
MDW
- SEA
1 stop8h 05m
Southwest
Deal found 6/6![Southwest logo]()
$361
This United Airlines deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/1612:10 pm
SEA
- ORD
1 stop9h 17m
United Airlines
Fri 10/91:30 pm
ORD
- SEA
Nonstop4h 36m
United Airlines
Deal found 6/5![United Airlines logo]()
$369
This Alaska Airlines deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/912:17 am
SEA
- ORD
Nonstop4h 03m
Alaska Airlines
Sun 8/166:42 pm
ORD
- SEA
Nonstop4h 52m
Alaska Airlines
Deal found 6/5![Alaska Airlines logo]()
$354
This Southwest deal was found by Cheapflights users on 6/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/111:45 pm
SEA
- MDW
1 stop7h 10m
Southwest
Sun 9/138:35 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 6/4![Southwest logo]()
$364
This United Airlines deal was found by Cheapflights users on 6/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/282:15 pm
SEA
- PIA
1 stop8h 04m
United Airlines
Sat 10/313:30 pm
PIA
- SEA
1 stop8h 59m
United Airlines
Deal found 6/4![United Airlines logo]()
$371
This Delta deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/237:20 am
SEA
- ORD
Nonstop4h 10m
Delta
Thu 7/96:55 am
ORD
- SEA
Nonstop4h 32m
Delta
Deal found 6/5![Delta logo]()
$375
This Kiwi.com deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/198:13 pm
SEA
- RFD
1 stop22h 32m
Multiple Airlines
Sun 8/239:35 pm
RFD
- SEA
1 stop15h 00m
Multiple Airlines
Deal found 6/2![Multiple Airlines logo]()
$379
This Alaska Airlines deal was found by Cheapflights users on 6/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/112:17 am
SEA
- ORD
Nonstop4h 03m
Alaska Airlines
Mon 7/66:00 am
ORD
- SEA
Nonstop4h 38m
Alaska Airlines
Deal found 6/1![Alaska Airlines logo]()
$355
This Southwest deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/91:50 pm
SEA
- MDW
1 stop7h 55m
Southwest
Sun 7/129:35 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 6/6![Southwest logo]()
$365
This Delta deal was found by Cheapflights users on 6/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/47:15 am
SEA
- BMI
2 stops14h 01m
Delta
Sun 9/66:00 am
BMI
- SEA
2 stops14h 44m
Delta
Deal found 6/3![Delta logo]()
$375
This Alaska Airlines deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/126:00 am
SEA
- ORD
Nonstop4h 03m
Alaska Airlines
Sun 8/168:20 pm
ORD
- SEA
Nonstop4h 44m
Alaska Airlines
Deal found 6/6![Alaska Airlines logo]()
$355
This Southwest deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/811:05 pm
SEA
- MDW
Nonstop3h 55m
Southwest
Sat 7/119:00 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 6/6![Southwest logo]()
$367
This Kiwi.com deal was found by Cheapflights users on 6/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/128:13 pm
SEA
- RFD
1 stop14h 21m
Multiple Airlines
Fri 8/149:24 pm
RFD
- SEA
2 stops17h 53m
Multiple Airlines
Deal found 6/3![Multiple Airlines logo]()
$405
This Alaska Airlines deal was found by Cheapflights users on 6/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/215:48 pm
SEA
- ORD
Nonstop4h 11m
Alaska Airlines
Sun 7/266:00 am
ORD
- SEA
Nonstop4h 38m
Alaska Airlines
Deal found 6/1![Alaska Airlines logo]()
$355
This United Airlines deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/257:11 am
SEA
- STL
2 stops11h 35m
United Airlines
Sat 8/2912:59 pm
STL
- SEA
1 stop8h 08m
United Airlines
Deal found 6/2![United Airlines logo]()
$434
This American Airlines deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/211:40 am
SEA
- EVV
1 stop9h 51m
American Airlines
Wed 7/86:55 pm
EVV
- SEA
1 stop7h 57m
American Airlines
Deal found 6/2![American Airlines logo]()
$486
This Delta deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/26:00 am
SEA
- MLI
1 stop8h 29m
Delta
Sun 10/45:10 pm
MLI
- SEA
1 stop8h 49m
Delta
Deal found 6/2![Delta logo]()
$414
This Southwest deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/1011:05 pm
SEA
- MDW
Nonstop3h 55m
Southwest
Fri 7/1710:00 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 6/5![Southwest logo]()
$386
This Alaska Airlines deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/155:48 pm
SEA
- ORD
Nonstop4h 11m
Alaska Airlines
Thu 8/203:43 pm
ORD
- SEA
Nonstop4h 33m
Alaska Airlines
Deal found 6/6![Alaska Airlines logo]()
$355
This United Airlines deal was found by Cheapflights users on 6/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/2710:40 pm
SEA
- CMI
1 stop8h 14m
United Airlines
Sat 10/311:32 pm
CMI
- SEA
1 stop7h 27m
United Airlines
Deal found 6/4![United Airlines logo]()
$438
This American Airlines deal was found by Cheapflights users on 6/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 7/47:26 am
SEA
- EVV
1 stop7h 17m
American Airlines
Fri 7/104:35 pm
EVV
- SEA
1 stop8h 25m
American Airlines
Deal found 6/4![American Airlines logo]()
$486
This Southwest deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/238:15 pm
SEA
- MDW
1 stop7h 30m
Southwest
Thu 7/910:00 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 6/5![Southwest logo]()
$391
This Alaska Airlines deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/166:21 am
SEA
- ORD
1 stop10h 36m
Alaska Airlines
Mon 7/208:20 pm
ORD
- SEA
Nonstop4h 44m
Alaska Airlines
Deal found 6/5![Alaska Airlines logo]()
$365
This American Airlines deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/255:10 am
SEA
- BMI
1 stop8h 42m
American Airlines
Mon 6/296:02 pm
BMI
- SEA
1 stop8h 39m
American Airlines
Deal found 6/2![American Airlines logo]()
$491
This United Airlines deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/3111:50 pm
SEA
- BMI
1 stop8h 07m
United Airlines
Tue 11/31:32 pm
BMI
- SEA
2 stops13h 01m
United Airlines
Deal found 6/5![United Airlines logo]()
$448
This Kiwi.com deal was found by Cheapflights users on 6/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/28:12 pm
SEA
- PIA
1 stop13h 47m
Multiple Airlines
Mon 7/612:49 pm
PIA
- SEA
1 stop23h 50m
Multiple Airlines
Deal found 6/3![Multiple Airlines logo]()
$509
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated June 6, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated June 6, 2026 and is based on user searches.
This Expedia deal was found by Cheapflights users on 6/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 6/612:45 pm
SEA
- ORD
Nonstop4h 18m
Multiple Airlines
Wed 6/109:48 pm
ORD
- SEA
1 stop18h 30m
Multiple Airlines
Deal found 6/4![Multiple Airlines logo]()
$349
This Expedia deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/810:31 am
SEA
- ORD
Nonstop4h 17m
Multiple Airlines
Tue 6/99:48 pm
ORD
- SEA
1 stop18h 30m
Multiple Airlines
Deal found 6/5![Multiple Airlines logo]()
$345
This Expedia deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/912:45 pm
SEA
- ORD
Nonstop4h 18m
Multiple Airlines
Thu 6/117:20 am
ORD
- SEA
1 stop29h 15m
Multiple Airlines
Deal found 6/5![Multiple Airlines logo]()
$348
This Booking.com deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/195:48 pm
SEA
- ORD
Nonstop4h 11m
Multiple Airlines
Sat 6/209:48 pm
ORD
- SEA
1 stop14h 00m
Multiple Airlines
Deal found 6/6![Multiple Airlines logo]()
$347
This CheapOair deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/247:41 pm
SEA
- ORD
1 stop23h 02m
Frontier
Sun 6/287:20 am
ORD
- SEA
1 stop29h 15m
Frontier
Deal found 6/6![Frontier logo]()
$346
This CheapOair deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/243:33 pm
SEA
- ORD
1 stop27h 10m
Frontier
Sat 6/279:48 pm
ORD
- SEA
1 stop14h 00m
Frontier
Deal found 6/5![Frontier logo]()
$350
This CheapOair deal was found by Cheapflights users on 6/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/27:41 pm
SEA
- ORD
1 stop23h 02m
Frontier
Sun 7/57:15 am
ORD
- SEA
1 stop29h 24m
Frontier
Deal found 6/6![Frontier logo]()
$344
This Delta deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/310:58 pm
SEA
- MLI
1 stop9h 26m
Delta
Tue 8/115:09 pm
MLI
- SEA
1 stop8h 48m
Delta
Deal found 6/2![Delta logo]()
$349
This Frontier deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/148:13 pm
SEA
- ORD
1 stop7h 24m
Frontier
Mon 7/209:57 pm
ORD
- SEA
1 stop13h 20m
Frontier
Deal found 6/2![Frontier logo]()
$352
This Kiwi.com deal was found by Cheapflights users on 6/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/1512:17 am
SEA
- ORD
Nonstop4h 03m
Alaska Airlines
Sun 7/196:00 am
ORD
- SEA
Nonstop4h 38m
Alaska Airlines
Deal found 6/4![Alaska Airlines logo]()
$351
This Southwest deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 7/2711:05 pm
SEA
- MDW
Nonstop3h 55m
Southwest
Tue 8/46:00 am
MDW
- SEA
1 stop7h 15m
Southwest
Deal found 6/5![Southwest logo]()
$350
This Southwest deal was found by Cheapflights users on 6/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/285:00 am
SEA
- MDW
Nonstop3h 55m
Southwest
Tue 8/46:00 am
MDW
- SEA
1 stop7h 15m
Southwest
Deal found 6/3![Southwest logo]()
$349
One-way flights from Seattle to IllinoisSearch for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated June 6, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated June 6, 2026.
This American Airlines deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/83:21 pm
SEA
- STL
1 stop6h 37m
American Airlines
Deal found 6/2![American Airlines logo]()
$140
This United Airlines deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/178:45 am
SEA
- STL
1 stop7h 32m
United Airlines
Deal found 6/2![United Airlines logo]()
$147
This Kiwi.com deal was found by Cheapflights users on 6/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/27:41 pm
SEA
- STL
1 stop21h 42m
Frontier
Deal found 6/3![Frontier logo]()
$150
This Kiwi.com deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/38:53 pm
SEA
- STL
1 stop19h 12m
Frontier
Deal found 6/5![Frontier logo]()
$158
This Super.com deal was found by Cheapflights users on 6/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/308:12 pm
SEA
- STL
1 stop20h 39m
Frontier
Deal found 6/3![Frontier logo]()
$160
This Frontier deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/18:12 pm
SEA
- STL
1 stop13h 06m
Frontier
Deal found 6/2![Frontier logo]()
$161
This American Airlines deal was found by Cheapflights users on 6/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/1211:16 pm
SEA
- STL
1 stop8h 08m
American Airlines
Deal found 6/1![American Airlines logo]()
$163
This Kiwi.com deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/309:16 pm
SEA
- MLI
1 stop12h 59m
Multiple Airlines
Deal found 6/2![Multiple Airlines logo]()
$164
This CheapOair deal was found by Cheapflights users on 6/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/87:06 pm
SEA
- STL
1 stop22h 17m
Frontier
Deal found 6/5![Frontier logo]()
$166
This United Airlines deal was found by Cheapflights users on 6/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/1711:49 pm
SEA
- STL
1 stop8h 18m
United Airlines
Deal found 6/2![United Airlines logo]()
$168
This Kiwi.com deal was found by Cheapflights users on 6/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/1110:34 am
SEA
- STL
2 stops35h 25m
Frontier
Deal found 6/3![Frontier logo]()
$169
This American Airlines deal was found by Cheapflights users on 6/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/251:17 am
SEA
- CMI
1 stop7h 24m
American Airlines
Deal found 6/1![American Airlines logo]()
$169
Find flight deals from Seattle to Illinois
Keep the following information in mind while searching for Seattle to Illinois flight deals. Data was last updated June 6, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $343 (American Airlines) |
One-way from | $140 (United Airlines) |
Popular in | June |
Cheapest in | February |
Average price | $376 |
Good round-trip deal | $378 or less |
Good one-way deal | $199 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Seattle to Illinois that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated June 6, 2026.
Use the filters below to find and compare flights from Seattle to Illinois that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
SeattleMoline
SEA - MLI
SEAMLI
Seattle/Tacoma Intl
Tue 7/14
5:05 am-4:11 pm
1 stop9h 06m
Moline Quad-City
Sat 7/18
6:50 pm-12:52 am
1 stop8h 02m
$349
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Thu 7/16
11:29 am-5:38 pm
Nonstop4h 09m
Chicago O'Hare Intl
Thu 7/16
6:42 pm-9:34 pm
Nonstop4h 52m
$350
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Sun 8/9
12:17 am-6:20 am
Nonstop4h 03m
Chicago O'Hare Intl
Sun 8/16
6:42 pm-9:34 pm
Nonstop4h 52m
$354
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Tue 7/7
5:40 pm-11:38 pm
Nonstop3h 58m
Chicago O'Hare Intl
Tue 7/14
5:55 pm-8:34 pm
Nonstop4h 39m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 7/1
12:17 am-6:20 am
Nonstop4h 03m
Chicago O'Hare Intl
Mon 7/6
6:00 am-8:38 am
Nonstop4h 38m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 8/12
6:00 am-12:03 pm
Nonstop4h 03m
Chicago O'Hare Intl
Sun 8/16
8:20 pm-11:04 pm
Nonstop4h 44m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Tue 7/21
5:48 pm-11:59 pm
Nonstop4h 11m
Chicago O'Hare Intl
Sun 7/26
6:00 am-8:38 am
Nonstop4h 38m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Sat 8/15
5:48 pm-11:59 pm
Nonstop4h 11m
Chicago O'Hare Intl
Thu 8/20
3:43 pm-6:16 pm
Nonstop4h 33m
$355
SeattleChicago
SEA - RFD
SEARFD
Seattle/Tacoma Intl
Wed 9/9
9:16 pm-8:39 pm
1 stop21h 23m
Chicago Greater Rockford
Sun 9/13
9:29 pm-9:51 am
2 stops14h 22m
$360
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Thu 10/1
5:00 am-10:55 am
Nonstop3h 55m
Chicago Midway
Mon 10/5
6:30 am-12:35 pm
1 stop8h 05m
$361
Showing 1-10 of 60 resultsSorted by cheapest first
Best time to book a flight from Seattle to Illinois
Have a flexible travel schedule? Discover the best time to fly to Illinois from Seattle with our price prediction graph.
SEA-MLI
SEA-ORD
SEA-RFD
SEA-MDW
SEA-PIA
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.
Cheapflights Insights
Everything you need to know about your flight from Seattle to Illinois
SEA-USIL
SEA-MLI
SEA-ORD
SEA-RFD
SEA-MDW
What is the cheapest month to book a flight from Seattle to Illinois?
Currently, January is the cheapest month in which you can book a flight from Seattle to Illinois (average of $47). Flying from Seattle to Illinois in March is currently the most expensive (average of $693). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.
What is the cheapest time of day to fly from SEA to IL?
Find hourly flight availability from Seattle to Illinois. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated June 6, 2026.
It’s typically best to fly out from Seattle to Illinois in the evening. Doing so could potentially save you 6% on the flight price compared to flying in the morning, which is usually more expensive.
Weekly flight availability from Seattle to Illinois
Explore weekly flight availability from Seattle to Illinois. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated June 6, 2026.
The most flights from SEA to USIL are scheduled on a Thursday (65 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (37 on average).
How much does it cost to fly round-trip from Seattle to Illinois?
How far ahead should I book a flight from Seattle to Illinois?
The price you pay for your flight from Seattle to Illinois may vary depending on when you book. For the best chance of a lower fare, look to book 83 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.
What is the cheapest day to fly from Seattle to Illinois?
Use this chart to determine the cheapest time to fly round-trip from Seattle to Illinois. Price data was last updated on May 30, 2026.
Travelers seeking maximum savings on their Seattle to Illinois flight should consider departing on Saturday afternoons when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
Reviews of airlines servicing Illinois
Get insights into the airlines that provide service to Illinois. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Illinois. Reviews last updated June 6, 2026.
Read through reviews of airlines operating flights from Seattle to Illinois, such as Southwest,Alaska Airlines, andDelta. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Boarding
8.1
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Boarding
8.1
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Boarding
8.1
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Boarding
8.1
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Boarding
8.1
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Boarding
8.1
Food
7.0
Crew
8.6
Overall
8.0
Comfort
8.0
Entertainment
7.5
Reviews
1 / 20
8.0
ExcellentLa Tracimeldamarcos,Jun 2026
LAX - SLC
Related info for your journey
Find useful and relevant information for your journey from Seattle to Illinois. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
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Alternative routes for Seattle to Illinois
See prices for flight routes from nearby airports that may be better suited for you.
Complete your trip
Complete your trip to Illinois by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Seattle to Illinois by cabin class
Find flights from Seattle to Illinois, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Seattle and Illinois flights
Browse other Seattle and Illinois flight options. Last updated on June 6, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Seattle to Illinois flights
Consider these flights traveling from Seattle to Illinois.
Top 7 airlines flying from Seattle to Illinois
Discover the top 7 airlines that operate flights from Seattle to Illinois. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated June 6, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$114 | Average$368 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$124 | Average$294 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$176 | Average$429 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$177 | Average$342 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$180 | Average$421 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$193 | Average$309 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$207 | Average$363 | FlexibilityNo cancel fee | On-time63% |