$88+ 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 6/1. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Jun 6 — Jun 131
Round-trip
1 adult, Economy
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Find cheap flights from Seattle to Illinois with Cheapflights
1. Tell us where you want to go
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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 May 7, 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 May 7, 2026.
This Frontier deal was found by Cheapflights users on 5/2. 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.
Fri 7/108:12 pm
SEA
- ORD
1 stop7h 16m
Frontier
Sat 7/189:57 pm
ORD
- SEA
1 stop13h 52m
Frontier
Deal found 5/2![Frontier logo]()
$245
This CheapOair deal was found by Cheapflights users on 5/3. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/137:41 pm
SEA
- ORD
1 stop23h 11m
Frontier
Mon 8/177:15 am
ORD
- SEA
1 stop29h 20m
Frontier
Deal found 5/3![Frontier logo]()
$248
This Frontier deal was found by Cheapflights users on 5/4. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/108:12 pm
SEA
- ORD
1 stop7h 16m
Frontier
Mon 7/139:57 pm
ORD
- SEA
1 stop13h 52m
Frontier
Deal found 5/4![Frontier logo]()
$250
This Frontier deal was found by Cheapflights users on 5/2. 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.
Fri 7/108:12 pm
SEA
- ORD
1 stop7h 16m
Frontier
Fri 7/179:57 pm
ORD
- SEA
1 stop13h 52m
Frontier
Deal found 5/2![Frontier logo]()
$251
This CheapOair deal was found by Cheapflights users on 5/5. 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.
Thu 8/277:41 pm
SEA
- ORD
1 stop23h 12m
Frontier
Sat 8/299:48 pm
ORD
- SEA
1 stop18h 16m
Frontier
Deal found 5/5![Frontier logo]()
$254
This CheapOair deal was found by Cheapflights users on 5/2. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 7/258:12 pm
SEA
- ORD
1 stop7h 16m
Frontier
Tue 7/287:15 am
ORD
- SEA
1 stop29h 24m
Frontier
Deal found 5/2![Frontier logo]()
$255
This Trip.com deal was found by Cheapflights users on 5/7. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/227:50 pm
SEA
- ORD
1 stop22h 42m
Frontier
Thu 5/288:46 pm
ORD
- SEA
1 stop23h 49m
Frontier
Deal found 5/7![Frontier logo]()
$257
This CheapOair deal was found by Cheapflights users on 5/5. 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.
Thu 6/113:33 pm
SEA
- ORD
1 stop27h 10m
Frontier
Fri 6/199:48 pm
ORD
- SEA
1 stop14h 00m
Frontier
Deal found 5/5![Frontier logo]()
$260
This CheapOair deal was found by Cheapflights users on 5/4. 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.
Thu 7/97:41 pm
SEA
- ORD
1 stop23h 11m
Frontier
Sun 7/127:15 am
ORD
- SEA
1 stop29h 24m
Frontier
Deal found 5/4![Frontier logo]()
$261
This Booking.com deal was found by Cheapflights users on 5/5. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/27:50 pm
SEA
- ORD
1 stop22h 42m
Frontier
Tue 6/97:20 am
ORD
- SEA
1 stop29h 15m
Frontier
Deal found 5/5![Frontier logo]()
$262
This Booking.com deal was found by Cheapflights users on 5/5. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/97:41 pm
SEA
- ORD
1 stop23h 02m
Frontier
Sat 6/139:48 pm
ORD
- SEA
1 stop18h 30m
Frontier
Deal found 5/5![Frontier logo]()
$263
This United Airlines deal was found by Cheapflights users on 5/4. 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 9/231:56 pm
SEA
- PIA
1 stop8h 26m
United Airlines
Sat 9/261:21 pm
PIA
- SEA
1 stop7h 38m
United Airlines
Deal found 5/4![United Airlines logo]()
$293
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 May 7, 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 May 7, 2026.
This Alaska Airlines deal was found by Cheapflights users on 5/6. 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 6/312:45 pm
SEA
- STL
Nonstop4h 00m
Alaska Airlines
Sat 6/67:41 pm
STL
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 5/6![Alaska Airlines logo]()
$317
This Delta deal was found by Cheapflights users on 5/4. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/235:40 pm
SEA
- ORD
Nonstop3h 58m
Delta
Mon 7/276:55 am
ORD
- SEA
Nonstop4h 32m
Delta
Deal found 5/4![Delta logo]()
$355
This United Airlines deal was found by Cheapflights users on 5/4. 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 8/45:15 pm
SEA
- ORD
Nonstop4h 07m
United Airlines
Tue 8/111:00 pm
ORD
- SEA
Nonstop4h 36m
United Airlines
Deal found 5/4![United Airlines logo]()
$355
This Southwest deal was found by Cheapflights users on 5/2. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/2411:05 pm
SEA
- MDW
Nonstop3h 55m
Southwest
Sat 6/279:00 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 5/2![Southwest logo]()
$355
This American Airlines deal was found by Cheapflights users on 5/3. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/105:10 am
SEA
- CMI
1 stop7h 05m
American Airlines
Tue 6/166:43 pm
CMI
- SEA
1 stop7h 58m
American Airlines
Deal found 5/3![American Airlines logo]()
$406
This Kiwi.com deal was found by Cheapflights users on 5/4. 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 7/88:12 pm
SEA
- RFD
1 stop14h 12m
Multiple Airlines
Sun 7/191:14 pm
RFD
- SEA
1 stop23h 25m
Multiple Airlines
Deal found 5/4![Multiple Airlines logo]()
$412
This Alaska Airlines deal was found by Cheapflights users on 5/6. 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 6/38:45 am
SEA
- STL
1 stop5h 52m
Alaska Airlines
Wed 6/107:56 pm
STL
- SEA
Nonstop4h 28m
Alaska Airlines
Deal found 5/6![Alaska Airlines logo]()
$352
This Delta deal was found by Cheapflights users on 5/6. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/105:40 pm
SEA
- ORD
Nonstop3h 58m
Delta
Mon 7/136:55 am
ORD
- SEA
Nonstop4h 32m
Delta
Deal found 5/6![Delta logo]()
$355
This Southwest deal was found by Cheapflights users on 5/5. 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 6/911:05 pm
SEA
- MDW
Nonstop3h 55m
Southwest
Tue 6/169:50 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 5/5![Southwest logo]()
$355
This United Airlines deal was found by Cheapflights users on 5/3. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/278:30 am
SEA
- STL
2 stops13h 27m
United Airlines
Sat 5/307:23 pm
STL
- SEA
1 stop7h 50m
United Airlines
Deal found 5/3![United Airlines logo]()
$374
This Alaska Airlines deal was found by Cheapflights users on 5/5. 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.
Wed 5/204:42 pm
SEA
- ORD
Nonstop4h 17m
Alaska Airlines
Sat 5/235:52 pm
ORD
- SEA
Nonstop4h 38m
Alaska Airlines
Deal found 5/5![Alaska Airlines logo]()
$355
This Delta deal was found by Cheapflights users on 5/2. 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 6/125:40 pm
SEA
- ORD
Nonstop3h 59m
Delta
Wed 6/176:55 am
ORD
- SEA
Nonstop4h 36m
Delta
Deal found 5/2![Delta logo]()
$355
This Southwest deal was found by Cheapflights users on 5/5. 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.
Thu 6/41:50 pm
SEA
- MDW
1 stop8h 05m
Southwest
Thu 6/1110:00 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 5/5![Southwest logo]()
$365
This Delta deal was found by Cheapflights users on 5/3. 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.
Sat 5/2310:59 am
SEA
- ORD
Nonstop4h 14m
Delta
Fri 5/2912:47 pm
ORD
- SEA
Nonstop4h 33m
Delta
Deal found 5/3![Delta logo]()
$355
This Alaska Airlines deal was found by Cheapflights users on 5/2. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/27:26 am
SEA
- ORD
1 stop9h 24m
Alaska Airlines
Sat 6/63:28 pm
ORD
- SEA
Nonstop4h 38m
Alaska Airlines
Deal found 5/2![Alaska Airlines logo]()
$365
This Southwest deal was found by Cheapflights users on 5/3. 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.
Thu 5/285:30 am
SEA
- MDW
1 stop6h 50m
Southwest
Thu 5/289:35 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 5/3![Southwest logo]()
$365
This American Airlines deal was found by Cheapflights users on 5/7. 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 6/65:10 am
SEA
- BMI
1 stop8h 42m
American Airlines
Sat 6/136:03 pm
BMI
- SEA
1 stop8h 38m
American Airlines
Deal found 5/7![American Airlines logo]()
$445
This Kiwi.com deal was found by Cheapflights users on 5/6. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/158:12 pm
SEA
- RFD
1 stop14h 12m
Multiple Airlines
Sun 7/191:14 pm
RFD
- SEA
1 stop23h 25m
Multiple Airlines
Deal found 5/6![Multiple Airlines logo]()
$448
This Delta deal was found by Cheapflights users on 5/4. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/227:20 am
SEA
- ORD
Nonstop4h 08m
Delta
Mon 7/276:55 am
ORD
- SEA
Nonstop4h 32m
Delta
Deal found 5/4![Delta logo]()
$355
This Southwest deal was found by Cheapflights users on 5/4. 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 8/46:35 pm
SEA
- MDW
1 stop8h 25m
Southwest
Mon 8/108:55 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 5/4![Southwest logo]()
$365
This Kiwi.com deal was found by Cheapflights users on 5/6. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/228:12 pm
SEA
- RFD
1 stop14h 12m
Multiple Airlines
Sun 7/261:14 pm
RFD
- SEA
1 stop23h 25m
Multiple Airlines
Deal found 5/6![Multiple Airlines logo]()
$448
This United Airlines deal was found by Cheapflights users on 5/4. 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 6/28:56 am
SEA
- STL
2 stops10h 25m
United Airlines
Sat 6/67:23 pm
STL
- SEA
1 stop7h 50m
United Airlines
Deal found 5/4![United Airlines logo]()
$453
This American Airlines deal was found by Cheapflights users on 5/4. 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 6/113:05 pm
SEA
- BMI
1 stop7h 30m
American Airlines
Sun 6/146:02 pm
BMI
- SEA
1 stop8h 39m
American Airlines
Deal found 5/4![American Airlines logo]()
$458
This Alaska Airlines deal was found by Cheapflights users on 5/4. 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/17:05 am
SEA
- STL
1 stop7h 32m
Alaska Airlines
Wed 6/37:41 pm
STL
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 5/4![Alaska Airlines logo]()
$387
This Delta deal was found by Cheapflights users on 5/4. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/95:40 pm
SEA
- ORD
Nonstop3h 58m
Delta
Thu 7/305:55 pm
ORD
- SEA
Nonstop4h 39m
Delta
Deal found 5/4![Delta logo]()
$355
This Southwest deal was found by Cheapflights users on 5/2. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/1611:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Sat 5/233:15 pm
MDW
- SEA
2 stops9h 45m
Southwest
Deal found 5/2![Southwest logo]()
$370
This United Airlines deal was found by Cheapflights users on 5/6. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/2811:20 pm
SEA
- MLI
2 stops11h 17m
United Airlines
Tue 6/21:15 pm
MLI
- SEA
1 stop7h 50m
United Airlines
Deal found 5/6![United Airlines logo]()
$454
This Kiwi.com deal was found by Cheapflights users on 5/7. 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 6/248:12 pm
SEA
- RFD
1 stop14h 11m
Multiple Airlines
Fri 6/2610:05 pm
RFD
- SEA
2 stops18h 13m
Multiple Airlines
Deal found 5/7![Multiple Airlines logo]()
$455
This American Airlines deal was found by Cheapflights users on 5/6. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/2410:23 am
SEA
- CMI
1 stop9h 38m
American Airlines
Tue 6/306:43 pm
CMI
- SEA
1 stop7h 58m
American Airlines
Deal found 5/6![American Airlines logo]()
$465
This Delta deal was found by Cheapflights users on 5/2. 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.
Mon 6/157:20 am
SEA
- ORD
Nonstop4h 10m
Delta
Wed 6/176:55 am
ORD
- SEA
Nonstop4h 36m
Delta
Deal found 5/2![Delta logo]()
$355
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated May 7, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated May 7, 2026 and is based on user searches.
This CheapOair deal was found by Cheapflights users on 5/4. 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.
Mon 5/187:50 pm
SEA
- ORD
1 stop22h 42m
Frontier
Tue 5/268:46 pm
ORD
- SEA
1 stop23h 49m
Frontier
Deal found 5/4![Frontier logo]()
$267
This Gotogate deal was found by Cheapflights users on 5/7. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/223:19 pm
SEA
- ORD
1 stop27h 13m
Frontier
Thu 5/288:46 pm
ORD
- SEA
1 stop23h 49m
Frontier
Deal found 5/7![Frontier logo]()
$265
This CheapOair deal was found by Cheapflights users on 5/4. 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.
Sat 5/2311:21 am
SEA
- ORD
1 stop17h 13m
Frontier
Tue 5/269:37 pm
ORD
- SEA
1 stop14h 29m
Frontier
Deal found 5/4![Frontier logo]()
$271
This Mytrip deal was found by Cheapflights users on 5/4. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/2311:21 am
SEA
- ORD
1 stop17h 13m
Frontier
Thu 5/288:46 pm
ORD
- SEA
1 stop23h 49m
Frontier
Deal found 5/4![Frontier logo]()
$272
This CheapOair deal was found by Cheapflights users on 5/2. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/2811:21 am
SEA
- ORD
1 stop17h 13m
Frontier
Sun 5/319:37 pm
ORD
- SEA
1 stop18h 24m
Frontier
Deal found 5/2![Frontier logo]()
$261
This Booking.com deal was found by Cheapflights users on 5/5. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/27:50 pm
SEA
- ORD
1 stop22h 42m
Frontier
Tue 6/97:20 am
ORD
- SEA
1 stop29h 15m
Frontier
Deal found 5/5![Frontier logo]()
$262
This Trip.com deal was found by Cheapflights users on 5/7. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/43:19 pm
SEA
- ORD
1 stop27h 13m
Frontier
Thu 6/117:20 am
ORD
- SEA
1 stop29h 15m
Frontier
Deal found 5/7![Frontier logo]()
$257
This Mytrip deal was found by Cheapflights users on 5/5. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 6/67:50 pm
SEA
- ORD
1 stop22h 42m
Frontier
Fri 6/127:20 am
ORD
- SEA
1 stop29h 15m
Frontier
Deal found 5/5![Frontier logo]()
$264
This Booking.com deal was found by Cheapflights users on 5/5. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/97:41 pm
SEA
- ORD
1 stop23h 02m
Frontier
Sat 6/139:48 pm
ORD
- SEA
1 stop18h 30m
Frontier
Deal found 5/5![Frontier logo]()
$263
This CheapOair deal was found by Cheapflights users on 5/5. 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.
Thu 6/113:33 pm
SEA
- ORD
1 stop27h 10m
Frontier
Fri 6/199:48 pm
ORD
- SEA
1 stop14h 00m
Frontier
Deal found 5/5![Frontier logo]()
$260
This Gotogate deal was found by Cheapflights users on 5/4. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/127:41 pm
SEA
- ORD
1 stop23h 02m
Frontier
Tue 6/167:20 am
ORD
- SEA
1 stop29h 15m
Frontier
Deal found 5/4![Frontier logo]()
$250
This Frontier deal was found by Cheapflights users on 5/5. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/162:20 pm
SEA
- ORD
1 stop12h 47m
Frontier
Thu 6/259:48 pm
ORD
- SEA
1 stop14h 00m
Frontier
Deal found 5/5![Frontier logo]()
$270
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 May 7, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated May 7, 2026.
This Kiwi.com deal was found by Cheapflights users on 5/6. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/17:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 5/6![Frontier logo]()
$88
This Super.com deal was found by Cheapflights users on 5/3. 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.
Wed 7/157:41 pm
SEA
- STL
1 stop21h 42m
Frontier
Deal found 5/3![Frontier logo]()
$109
This Super.com deal was found by Cheapflights users on 5/3. 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.
Mon 5/1811:37 am
SEA
- STL
1 stop28h 29m
Frontier
Deal found 5/3![Frontier logo]()
$110
This Kiwi.com deal was found by Cheapflights users on 5/7. 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 6/87:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 5/7![Frontier logo]()
$111
This CheapOair deal was found by Cheapflights users on 5/6. 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 7/88:12 pm
SEA
- STL
1 stop15h 55m
Frontier
Deal found 5/6![Frontier logo]()
$116
This Kiwi.com deal was found by Cheapflights users on 5/6. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/211:21 am
SEA
- STL
2 stops30h 02m
Frontier
Deal found 5/6![Frontier logo]()
$118
This Trip.com deal was found by Cheapflights users on 5/7. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 6/67:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 5/7![Frontier logo]()
$123
This Jettzy deal was found by Cheapflights users on 5/4. 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 Jettzy is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 7/278:12 pm
SEA
- ORD
1 stop7h 16m
Frontier
Deal found 5/4![Frontier logo]()
$127
This Super.com deal was found by Cheapflights users on 5/3. 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.
Mon 5/253:19 pm
SEA
- ORD
1 stop27h 13m
Frontier
Deal found 5/3![Frontier logo]()
$129
This Booking.com deal was found by Cheapflights users on 5/2. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 6/137:41 pm
SEA
- ORD
1 stop23h 02m
Frontier
Deal found 5/2![Frontier logo]()
$131
This Trip.com deal was found by Cheapflights users on 5/3. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/87:50 pm
SEA
- ORD
1 stop22h 53m
Frontier
Deal found 5/3![Frontier logo]()
$134
This Super.com deal was found by Cheapflights users on 5/2. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/187:50 pm
SEA
- ORD
1 stop22h 42m
Frontier
Deal found 5/2![Frontier logo]()
$135
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 May 7, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $245 (Frontier) |
One-way from | $88 (Kiwi.com) |
Popular in | December |
Cheapest in | February |
Average price | $319 |
Good round-trip deal | $362 or less |
Good one-way deal | $196 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 May 7, 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
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Wed 6/3
12:45 pm-6:45 pm
Nonstop4h 00m
Lambert-St Louis
Sat 6/6
7:41 pm-10:11 pm
Nonstop4h 30m
$317
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Wed 6/3
8:45 am-4:37 pm
1 stop5h 52m
Lambert-St Louis
Wed 6/10
7:56 pm-10:24 pm
Nonstop4h 28m
$352
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Thu 7/23
5:40 pm-11:38 pm
Nonstop3h 58m
Chicago O'Hare Intl
Mon 7/27
6:55 am-9:27 am
Nonstop4h 32m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Tue 8/4
5:15 pm-11:22 pm
Nonstop4h 07m
Chicago O'Hare Intl
Tue 8/11
1:00 pm-3:36 pm
Nonstop4h 36m
$355
Quickest round-trip
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Wed 6/24
11:05 pm-5:00 am
Nonstop3h 55m
Chicago Midway
Sat 6/27
9:00 pm-11:30 pm
Nonstop4h 30m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Fri 7/10
5:40 pm-11:38 pm
Nonstop3h 58m
Chicago O'Hare Intl
Mon 7/13
6:55 am-9:27 am
Nonstop4h 32m
$355
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Tue 6/9
11:05 pm-5:00 am
Nonstop3h 55m
Chicago Midway
Tue 6/16
9:50 pm-12:20 am
Nonstop4h 30m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 5/20
4:42 pm-10:59 pm
Nonstop4h 17m
Chicago O'Hare Intl
Sat 5/23
5:52 pm-8:30 pm
Nonstop4h 38m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Fri 6/12
5:40 pm-11:39 pm
Nonstop3h 59m
Chicago O'Hare Intl
Wed 6/17
6:55 am-9:31 am
Nonstop4h 36m
$355
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Sat 5/23
10:59 am-5:13 pm
Nonstop4h 14m
Chicago O'Hare Intl
Fri 5/29
12:47 pm-3:20 pm
Nonstop4h 33m
$355
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-ORD
SEA-PIA
SEA-STL
SEA-MDW
SEA-CMI
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-ORD
SEA-PIA
SEA-STL
SEA-MDW
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 81 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.
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 $665). 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 May 7, 2026.
It’s typically best to fly out from Seattle to Illinois in the evening. Doing so could potentially save you 7% on the flight price compared to flying in the morning, which is usually more expensive.
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 2, 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.
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 May 7, 2026.
The most flights from SEA to USIL are scheduled on a Thursday (57 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (34 on average).
How much does it cost to fly round-trip from Seattle to Illinois?
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 May 7, 2026.
Read through reviews of airlines operating flights from Seattle to Illinois, such as Alaska Airlines,Southwest, andDelta. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Crew
8.5
Comfort
7.8
Entertainment
7.0
Boarding
8.1
Food
7.1
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Crew
8.5
Comfort
7.8
Entertainment
7.0
Boarding
8.1
Food
7.1
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Crew
8.5
Comfort
7.8
Entertainment
7.0
Boarding
8.1
Food
7.1
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Crew
8.5
Comfort
7.8
Entertainment
7.0
Boarding
8.1
Food
7.1
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Crew
8.5
Comfort
7.8
Entertainment
7.0
Boarding
8.1
Food
7.1
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
Crew
8.5
Comfort
7.8
Entertainment
7.0
Boarding
8.1
Food
7.1
Overall
7.9
Reviews
1 / 20
4.0
OkayAnonymous,Dec 2025
SEA - MSY
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 May 7, 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 May 7, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$108 | Average$351 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$121 | Average$221 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$164 | Average$428 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$170 | Average$318 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$177 | Average$357 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$177 | Average$427 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$193 | Average$308 | FlexibilityNo cancel fee | On-time62% |