$80+ Cheap flights from Illinois to Seattle (SEA)
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 6/9. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — SEA
Apr 23 — Apr 301
Round-trip
1 adult, Economy
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Cheapest flights from Illinois to SeattleExplore the most affordable flight options available from Illinois to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on March 24, 2026.
Explore the most affordable flight options available from Illinois to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on March 24, 2026.
This Southwest deal was found by Cheapflights users on 3/23. 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 4/153:55 pm
STL
- SEA
1 stop10h 15m
Southwest
Sat 4/185:45 am
SEA
- STL
2 stops10h 25m
Southwest
Deal found 3/23![Southwest logo]()
$195
This CheapOair deal was found by Cheapflights users on 3/20. 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 5/59:42 pm
ORD
- SEA
1 stop14h 07m
Frontier
Thu 5/77:50 pm
SEA
- ORD
1 stop22h 47m
Frontier
Deal found 3/20![Frontier logo]()
$196
This CheapOair deal was found by Cheapflights users on 3/20. 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 5/88:08 pm
STL
- SEA
1 stop15h 41m
Frontier
Sat 5/1611:37 am
SEA
- STL
1 stop21h 44m
Frontier
Deal found 3/20![Frontier logo]()
$196
This Booking.com deal was found by Cheapflights users on 3/24. 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.
Wed 4/228:58 pm
ORD
- SEA
1 stop24h 53m
Frontier
Mon 4/2710:11 pm
SEA
- ORD
1 stop29h 57m
Frontier
Deal found 3/24![Frontier logo]()
$198
This Southwest deal was found by Cheapflights users on 3/24. 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 5/17:20 pm
STL
- SEA
1 stop7h 20m
Southwest
Tue 5/58:25 am
SEA
- STL
1 stop7h 30m
Southwest
Deal found 3/24![Southwest logo]()
$199
This Kiwi.com deal was found by Cheapflights users on 3/20. 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 4/134:46 pm
ORD
- SEA
2 stops18h 41m
Frontier
Wed 4/158:07 pm
SEA
- ORD
1 stop11h 43m
Frontier
Deal found 3/20![Frontier logo]()
$200
This Southwest deal was found by Cheapflights users on 3/23. 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 5/55:30 am
STL
- SEA
2 stops14h 30m
Southwest
Sat 5/95:45 am
SEA
- STL
2 stops10h 25m
Southwest
Deal found 3/23![Southwest logo]()
$200
This Kiwi.com deal was found by Cheapflights users on 3/20. 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 4/208:58 pm
ORD
- SEA
2 stops14h 29m
Frontier
Sun 4/269:54 pm
SEA
- ORD
1 stop30h 14m
Frontier
Deal found 3/20![Frontier logo]()
$201
This Southwest deal was found by Cheapflights users on 3/23. 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 4/161:45 pm
STL
- SEA
1 stop12h 20m
Southwest
Mon 4/2011:55 pm
SEA
- STL
1 stop7h 35m
Southwest
Deal found 3/23![Southwest logo]()
$205
This American Airlines deal was found by Cheapflights users on 3/24. 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.
Mon 4/205:21 pm
STL
- SEA
1 stop9h 15m
American Airlines
Tue 4/283:17 pm
SEA
- STL
1 stop6h 29m
American Airlines
Deal found 3/24![American Airlines logo]()
$209
This Southwest deal was found by Cheapflights users on 3/23. 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 4/295:30 am
STL
- SEA
2 stops14h 30m
Southwest
Fri 5/12:50 pm
SEA
- STL
1 stop7h 25m
Southwest
Deal found 3/23![Southwest logo]()
$210
This Kiwi.com deal was found by Cheapflights users on 3/20. 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 4/132:29 pm
ORD
- SEA
1 stop20h 58m
Multiple Airlines
Tue 4/217:12 pm
SEA
- ORD
2 stops34h 53m
Multiple Airlines
Deal found 3/20![Multiple Airlines logo]()
$211
Best flights from Illinois to SeattleDiscover carefully curated flight deals from Illinois to Seattle that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated March 24, 2026.
Discover carefully curated flight deals from Illinois to Seattle that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated March 24, 2026.
This United Airlines deal was found by Cheapflights users on 3/24. 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 4/294:20 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Tue 5/53:40 pm
SEA
- ORD
1 stop6h 17m
United Airlines
Deal found 3/24![United Airlines logo]()
$235
This Southwest deal was found by Cheapflights users on 3/19. 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 4/209:35 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Sun 4/269:25 pm
SEA
- MDW
1 stop6h 20m
Southwest
Deal found 3/19![Southwest logo]()
$247
This Delta deal was found by Cheapflights users on 3/19. 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 4/231:36 pm
ORD
- SEA
1 stop10h 14m
Delta
Tue 4/287:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Deal found 3/19![Delta logo]()
$247
This Alaska Airlines deal was found by Cheapflights users on 3/23. 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 5/68:48 pm
ORD
- SEA
Nonstop4h 41m
Alaska Airlines
Sat 5/99:07 am
SEA
- ORD
1 stop7h 56m
Alaska Airlines
Deal found 3/23![Alaska Airlines logo]()
$250
This Southwest deal was found by Cheapflights users on 3/22. 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 4/215:30 am
MDW
- SEA
1 stop7h 50m
Southwest
Tue 4/286:30 am
SEA
- MDW
2 stops8h 05m
Southwest
Deal found 3/22![Southwest logo]()
$251
This Alaska Airlines deal was found by Cheapflights users on 3/21. 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 4/286:00 am
ORD
- SEA
Nonstop4h 32m
Alaska Airlines
Sat 5/25:42 pm
SEA
- ORD
Nonstop4h 17m
Alaska Airlines
Deal found 3/21![Alaska Airlines logo]()
$255
This Delta deal was found by Cheapflights users on 3/19. 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 4/146:00 pm
ORD
- SEA
Nonstop4h 43m
Delta
Sat 4/186:00 am
SEA
- ORD
1 stop8h 18m
Delta
Deal found 3/19![Delta logo]()
$256
This American Airlines deal was found by Cheapflights users on 3/20. 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 5/75:45 am
SPI
- SEA
1 stop8h 44m
American Airlines
Mon 5/113:17 pm
SEA
- SPI
1 stop6h 21m
American Airlines
Deal found 3/20![American Airlines logo]()
$537
This Delta deal was found by Cheapflights users on 3/19. 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 5/117:13 pm
MDW
- SEA
1 stop6h 31m
Delta
Mon 5/1811:05 pm
SEA
- MDW
1 stop7h 38m
Delta
Deal found 3/19![Delta logo]()
$257
This United Airlines deal was found by Cheapflights users on 3/19. 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 5/267:48 pm
ORD
- SEA
Nonstop4h 51m
United Airlines
Fri 5/292:36 pm
SEA
- ORD
1 stop6h 43m
United Airlines
Deal found 3/19![United Airlines logo]()
$287
This Southwest deal was found by Cheapflights users on 3/19. 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 5/199:40 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Mon 5/2511:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Deal found 3/19![Southwest logo]()
$287
This Delta deal was found by Cheapflights users on 3/22. 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 6/205:42 pm
STL
- SEA
1 stop8h 17m
Delta
Sat 6/279:45 pm
SEA
- STL
1 stop9h 47m
Delta
Deal found 3/22![Delta logo]()
$274
This United Airlines deal was found by Cheapflights users on 3/23. 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 6/31:32 pm
CMI
- SEA
1 stop7h 34m
United Airlines
Tue 6/911:52 pm
SEA
- CMI
1 stop7h 02m
United Airlines
Deal found 3/23![United Airlines logo]()
$328
This Southwest deal was found by Cheapflights users on 3/22. 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 5/279:40 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Wed 6/35:35 pm
SEA
- MDW
1 stop9h 50m
Southwest
Deal found 3/22![Southwest logo]()
$300
This Delta deal was found by Cheapflights users on 3/21. 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 5/157:59 pm
STL
- SEA
1 stop6h 13m
Delta
Sat 5/235:30 am
SEA
- STL
1 stop9h 46m
Delta
Deal found 3/21![Delta logo]()
$274
This Alaska Airlines deal was found by Cheapflights users on 3/21. 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 5/46:00 am
ORD
- SEA
Nonstop4h 32m
Alaska Airlines
Thu 5/712:29 am
SEA
- ORD
Nonstop4h 11m
Alaska Airlines
Deal found 3/21![Alaska Airlines logo]()
$355
This KAYAK deal was found by Cheapflights users on 3/19. 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 KAYAK is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 4/269:54 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Sun 5/310:53 pm
SEA
- ORD
Nonstop4h 10m
United Airlines
Deal found 3/19![United Airlines logo]()
$331
This Southwest deal was found by Cheapflights users on 3/21. 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 4/134:35 pm
MDW
- SEA
2 stops10h 20m
Southwest
Wed 4/1511:45 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Deal found 3/21![Southwest logo]()
$320
This United Airlines deal was found by Cheapflights users on 3/20. 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 7/257:34 pm
CMI
- SEA
1 stop6h 40m
United Airlines
Thu 7/3010:40 pm
SEA
- CMI
1 stop8h 14m
United Airlines
Deal found 3/20![United Airlines logo]()
$353
This Southwest deal was found by Cheapflights users on 3/19. 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 4/34:55 pm
ORD
- SEA
1 stop10h 30m
Southwest
Wed 4/88:25 am
SEA
- ORD
1 stop12h 30m
Southwest
Deal found 3/19![Southwest logo]()
$322
This Delta deal was found by Cheapflights users on 3/19. 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 4/216:00 pm
ORD
- SEA
Nonstop4h 43m
Delta
Thu 4/3011:59 pm
SEA
- ORD
1 stop6h 39m
Delta
Deal found 3/19![Delta logo]()
$344
This Alaska Airlines deal was found by Cheapflights users on 3/22. 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 5/55:15 am
MLI
- SEA
1 stop7h 25m
Alaska Airlines
Sat 5/91:28 pm
SEA
- MLI
1 stop8h 26m
Alaska Airlines
Deal found 3/22![Alaska Airlines logo]()
$439
This Southwest deal was found by Cheapflights users on 3/21. 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 5/57:45 am
ORD
- SEA
1 stop7h 50m
Southwest
Thu 5/76:30 am
SEA
- ORD
2 stops10h 05m
Southwest
Deal found 3/21![Southwest logo]()
$330
This American Airlines deal was found by Cheapflights users on 3/23. 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.
Fri 4/102:46 pm
BMI
- SEA
1 stop9h 52m
American Airlines
Sun 4/121:19 pm
SEA
- BMI
1 stop8h 33m
American Airlines
Deal found 3/23![American Airlines logo]()
$549
This Delta deal was found by Cheapflights users on 3/24. 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 4/216:00 pm
ORD
- SEA
Nonstop4h 43m
Delta
Sun 4/2611:59 pm
SEA
- ORD
1 stop6h 39m
Delta
Deal found 3/24![Delta logo]()
$346
This United Airlines deal was found by Cheapflights users on 3/24. 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.
Sun 5/317:23 pm
STL
- SEA
1 stop8h 06m
United Airlines
Tue 6/911:52 pm
SEA
- STL
1 stop6h 49m
United Airlines
Deal found 3/24![United Airlines logo]()
$389
This Alaska Airlines deal was found by Cheapflights users on 3/22. 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 9/16:00 am
MLI
- SEA
1 stop6h 41m
Alaska Airlines
Tue 9/87:00 am
SEA
- MLI
2 stops14h 23m
Alaska Airlines
Deal found 3/22![Alaska Airlines logo]()
$444
This Southwest deal was found by Cheapflights users on 3/20. 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 4/134:35 pm
MDW
- SEA
2 stops10h 20m
Southwest
Tue 4/216:30 am
SEA
- MDW
2 stops8h 05m
Southwest
Deal found 3/20![Southwest logo]()
$335
This United Airlines deal was found by Cheapflights users on 3/22. 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 5/25:30 pm
PIA
- SEA
1 stop7h 17m
United Airlines
Tue 5/52:27 pm
SEA
- PIA
1 stop6h 22m
United Airlines
Deal found 3/22![United Airlines logo]()
$391
This American Airlines deal was found by Cheapflights users on 3/20. 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 4/45:00 am
SPI
- SEA
2 stops10h 52m
American Airlines
Wed 4/811:55 pm
SEA
- SPI
2 stops12h 24m
American Airlines
Deal found 3/20![American Airlines logo]()
$577
Last-minute flights from Illinois to SeattleDiscover last-minute flight deals from Illinois to Seattle. Data last updated March 24, 2026 and is based on user searches.
Discover last-minute flight deals from Illinois to Seattle. Data last updated March 24, 2026 and is based on user searches.
This Southwest deal was found by Cheapflights users on 3/23. 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 4/153:55 pm
STL
- SEA
1 stop10h 15m
Southwest
Sat 4/185:45 am
SEA
- STL
2 stops10h 25m
Southwest
Deal found 3/23![Southwest logo]()
$195
This Southwest deal was found by Cheapflights users on 3/24. 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 4/159:40 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Wed 4/2211:45 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Deal found 3/24![Southwest logo]()
$225
This Southwest deal was found by Cheapflights users on 3/23. 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 4/161:45 pm
STL
- SEA
1 stop12h 20m
Southwest
Mon 4/2011:55 pm
SEA
- STL
1 stop7h 35m
Southwest
Deal found 3/23![Southwest logo]()
$205
This CheapOair deal was found by Cheapflights users on 3/23. 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 4/208:17 pm
STL
- SEA
1 stop15h 10m
Frontier
Wed 4/297:12 pm
SEA
- STL
1 stop22h 09m
Frontier
Deal found 3/23![Frontier logo]()
$196
This American Airlines deal was found by Cheapflights users on 3/24. 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.
Mon 4/205:21 pm
STL
- SEA
1 stop9h 15m
American Airlines
Tue 4/283:17 pm
SEA
- STL
1 stop6h 29m
American Airlines
Deal found 3/24![American Airlines logo]()
$209
This American Airlines deal was found by Cheapflights users on 3/23. 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 4/215:21 pm
STL
- SEA
1 stop9h 15m
American Airlines
Fri 4/2411:33 pm
SEA
- STL
1 stop6h 54m
American Airlines
Deal found 3/23![American Airlines logo]()
$199
This Delta deal was found by Cheapflights users on 3/23. 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 4/227:00 am
STL
- SEA
1 stop7h 25m
Delta
Sun 4/264:36 pm
SEA
- STL
1 stop5h 49m
Delta
Deal found 3/23![Delta logo]()
$213
This Southwest deal was found by Cheapflights users on 3/23. 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 4/225:30 am
STL
- SEA
2 stops14h 30m
Southwest
Sun 4/2611:55 pm
SEA
- STL
1 stop7h 10m
Southwest
Deal found 3/23![Southwest logo]()
$220
This Southwest deal was found by Cheapflights users on 3/23. 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 4/225:30 am
STL
- SEA
2 stops14h 30m
Southwest
Wed 4/296:50 am
SEA
- STL
2 stops9h 15m
Southwest
Deal found 3/23![Southwest logo]()
$225
This Delta deal was found by Cheapflights users on 3/24. 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 4/236:45 pm
STL
- SEA
1 stop7h 14m
Delta
Sun 4/261:30 pm
SEA
- STL
1 stop8h 55m
Delta
Deal found 3/24![Delta logo]()
$224
This CheapOair deal was found by Cheapflights users on 3/24. 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 4/258:17 pm
STL
- SEA
1 stop15h 10m
Frontier
Sat 5/27:12 pm
SEA
- STL
1 stop22h 09m
Frontier
Deal found 3/24![Frontier logo]()
$221
This Southwest deal was found by Cheapflights users on 3/23. 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 4/295:30 am
STL
- SEA
2 stops14h 30m
Southwest
Fri 5/12:50 pm
SEA
- STL
1 stop7h 25m
Southwest
Deal found 3/23![Southwest logo]()
$210
One-way flights from Illinois to SeattleSearch for one-way flight options from Illinois to Seattle. Find affordable one-way fares based on user searches. Data last updated March 24, 2026.
Search for one-way flight options from Illinois to Seattle. Find affordable one-way fares based on user searches. Data last updated March 24, 2026.
This Southwest deal was found by Cheapflights users on 3/24. 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 6/95:50 am
STL
- SEA
1 stop6h 30m
Southwest
Deal found 3/24![Southwest logo]()
$80
This Kiwi.com deal was found by Cheapflights users on 3/19. 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.
Fri 4/248:06 pm
STL
- SEA
1 stop15h 21m
Frontier
Deal found 3/19![Frontier logo]()
$81
This CheapOair deal was found by Cheapflights users on 3/21. 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 4/208:17 pm
STL
- SEA
1 stop15h 10m
Frontier
Deal found 3/21![Frontier logo]()
$86
This Delta deal was found by Cheapflights users on 3/24. 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 6/27:59 pm
STL
- SEA
1 stop6h 11m
Delta
Deal found 3/24![Delta logo]()
$89
This Southwest deal was found by Cheapflights users on 3/23. 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 4/221:45 pm
STL
- SEA
1 stop12h 25m
Southwest
Deal found 3/23![Southwest logo]()
$91
This Kiwi.com deal was found by Cheapflights users on 3/19. 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 4/168:06 pm
STL
- SEA
1 stop20h 59m
Frontier
Deal found 3/19![Frontier logo]()
$95
This Trip.com deal was found by Cheapflights users on 3/20. 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 4/32:29 pm
ORD
- SEA
1 stop23h 08m
Frontier
Deal found 3/20![Frontier logo]()
$107
This Expedia deal was found by Cheapflights users on 3/23. 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.
Sun 5/109:42 pm
ORD
- SEA
1 stop14h 07m
Frontier
Deal found 3/23![Frontier logo]()
$111
This Kiwi.com deal was found by Cheapflights users on 3/20. 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 5/119:18 pm
STL
- SEA
2 stops14h 31m
Frontier
Deal found 3/20![Frontier logo]()
$111
This Southwest deal was found by Cheapflights users on 3/22. 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 6/99:50 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/22![Southwest logo]()
$113
This United Airlines deal was found by Cheapflights users on 3/24. 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 4/214:20 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Deal found 3/24![United Airlines logo]()
$113
This Kiwi.com deal was found by Cheapflights users on 3/19. 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 4/204:14 pm
MDW
- SEA
2 stops43h 13m
Frontier
Deal found 3/19![Frontier logo]()
$117
Find flight deals from Illinois to Seattle
Keep the following information in mind while searching for Illinois to Seattle flight deals. Data was last updated March 24, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $195 (Southwest) |
One-way from | $80 (Southwest) |
Popular in | June |
Cheapest in | January |
Average price | $315 |
Good round-trip deal | $235 or less |
Good one-way deal | $122 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Illinois to Seattle 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 March 24, 2026.
Use the filters below to find and compare flights from Illinois to Seattle that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
ChicagoSeattle
ORD - SEA
ORDSEA
Chicago O'Hare Intl
Wed 4/29
4:20 pm-7:00 pm
Nonstop4h 40m
Seattle/Tacoma Intl
Tue 5/5
3:40 pm-11:57 pm
1 stop6h 17m
$235
ChicagoSeattle
MDW - SEA
MDWSEA
Chicago Midway
Mon 4/20
9:35 pm-12:05 am
Nonstop4h 30m
Seattle/Tacoma Intl
Sun 4/26
9:25 pm-5:45 am
1 stop6h 20m
$247
ChicagoSeattle
ORD - SEA
ORDSEA
Chicago O'Hare Intl
Thu 4/23
1:36 pm-9:50 pm
1 stop10h 14m
Seattle/Tacoma Intl
Tue 4/28
7:15 am-1:23 pm
Nonstop4h 08m
$247
ChicagoSeattle
ORD - SEA
ORDSEA
Chicago O'Hare Intl
Wed 5/6
8:48 pm-11:29 pm
Nonstop4h 41m
Seattle/Tacoma Intl
Sat 5/9
9:07 am-7:03 pm
1 stop7h 56m
$250
ChicagoSeattle
MDW - SEA
MDWSEA
Chicago Midway
Tue 4/21
5:30 am-11:20 am
1 stop7h 50m
Seattle/Tacoma Intl
Tue 4/28
6:30 am-4:35 pm
2 stops8h 05m
$251
ChicagoSeattle
ORD - SEA
ORDSEA
Chicago O'Hare Intl
Tue 4/28
6:00 am-8:32 am
Nonstop4h 32m
Seattle/Tacoma Intl
Sat 5/2
5:42 pm-11:59 pm
Nonstop4h 17m
$255
ChicagoSeattle
ORD - SEA
ORDSEA
Chicago O'Hare Intl
Tue 4/14
6:00 pm-8:43 pm
Nonstop4h 43m
Seattle/Tacoma Intl
Sat 4/18
6:00 am-4:18 pm
1 stop8h 18m
$256
ChicagoSeattle
MDW - SEA
MDWSEA
Chicago Midway
Mon 5/11
7:13 pm-11:44 pm
1 stop6h 31m
Seattle/Tacoma Intl
Mon 5/18
11:05 pm-8:43 am
1 stop7h 38m
$257
St. LouisSeattle
STL - SEA
STLSEA
Lambert-St Louis
Sat 6/20
5:42 pm-11:59 pm
1 stop8h 17m
Seattle/Tacoma Intl
Sat 6/27
9:45 pm-9:32 am
1 stop9h 47m
$274
St. LouisSeattle
STL - SEA
STLSEA
Lambert-St Louis
Fri 5/15
7:59 pm-12:12 am
1 stop6h 13m
Seattle/Tacoma Intl
Sat 5/23
5:30 am-5:16 pm
1 stop9h 46m
$274
Showing 1-10 of 60 resultsSorted by cheapest first
Best time to book a flight from Illinois to Seattle
Have a flexible travel schedule? Discover the best time to fly to Seattle from Illinois with our price prediction graph.
STL-SEA
ORD-SEA
MDW-SEA
CMI-SEA
EVV-SEA
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 Illinois to Seattle
USIL-SEA
STL-SEA
ORD-SEA
MDW-SEA
CMI-SEA
What is the cheapest month to book a flight from Illinois to Seattle?
Currently, October is the cheapest month in which you can book a flight from Illinois to Seattle (average of $112). Flying from Illinois to Seattle in December is currently the most expensive (average of $178). 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 IL to SEA?
Find hourly flight availability from Illinois to Seattle. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated March 24, 2026.
One of the essential ways to save on airfare from Illinois to Seattle is to remain as flexible as possible. Flights that are in the afternoon tend to be the most expensive. A flight in the evening could potentially save you up to 29% on airfare.
What is the cheapest day to fly from Illinois to Seattle?
Use this chart to determine the cheapest time to fly round-trip from Illinois to Seattle. Price data was last updated on March 23, 2026.
Travelers seeking maximum savings on their Illinois to Seattle flight should consider departing on Monday evenings when fares are most often at their lowest. Monday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.
Weekly flight availability from Illinois to Seattle
Explore weekly flight availability from Illinois to Seattle. 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 March 24, 2026.
The most flights from USIL to SEA are scheduled on a Monday (37 on average). You will have fewer flight options on Sunday, which is when the least amount of flights are scheduled (19 on average).
Related info for your journey
Find useful and relevant information for your journey from Illinois to Seattle. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
Traveling to a place near Seattle?
Book flights to Seattle if you plan to visit one of these locationsSeaTac
Tacoma
Ocean Shores
Olympia
Kent
Lynnwood
Edmonds
Lacey
Renton
Puyallup
Kirkland
Snoqualmie
Ellensburg
Tukwila
Fife
Lakewood
Leavenworth
Issaquah
Aberdeen
Shoreline
Browse thousands of different options on Cheapflights for your next trip
Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.
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Alternative routes for Illinois to Seattle
See prices for flight routes from nearby airports that may be better suited for you.
Complete your trip
Complete your trip to Seattle by adding a car rental and/or hotel reservation to your travel itinerary.
Search flights from Illinois to Seattle by cabin class
Find flights from Illinois to Seattle, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Illinois and Seattle flights
Browse other Illinois and Seattle flight options. Last updated on March 24, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Other flights to Seattle
Explore flights to Seattle departing from other origins. Flights are based on user searches made on Cheapflights and were last updated on March 24, 2026.
Illinois to Seattle flights
Consider these flights traveling from Illinois to Seattle.
Top 7 airlines flying from Illinois to Seattle
Discover the top 7 airlines that operate flights from Illinois to Seattle. 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 March 24, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$84 | Average$229 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$108 | Average$252 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$153 | Average$258 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$168 | Average$436 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$171 | Average$463 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$172 | Average$436 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$194 | Average$373 | FlexibilityNo cancel fee | On-time63% |