$69+ 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 9/15. Fares are subject to change and may not be available on all flights or dates of travel.
ORD — SEA
Aug 31 — Sep 71
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 August 1, 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 August 1, 2026.
This United Airlines deal was found by Cheapflights users on 8/1. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/113:35 pm
PIA
- SEA
1 stop9h 10m
United Airlines
Sat 9/1911:00 pm
SEA
- PIA
1 stop8h 57m
United Airlines
Deal found 8/1![United Airlines logo]()
$281
This Kiwi.com deal was found by Cheapflights users on 7/28. 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.
Sun 10/112:05 pm
MLI
- SEA
1 stop21h 55m
Multiple Airlines
Wed 10/219:16 pm
SEA
- MLI
1 stop12h 29m
Multiple Airlines
Deal found 7/28![Multiple Airlines logo]()
$286
This United Airlines deal was found by Cheapflights users on 7/28. 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 9/128:45 am
PIA
- SEA
2 stops9h 29m
United Airlines
Sat 9/1911:00 pm
SEA
- PIA
1 stop8h 57m
United Airlines
Deal found 7/28![United Airlines logo]()
$286
This Southwest deal was found by Cheapflights users on 8/1. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/37:05 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Tue 10/611:30 am
SEA
- MDW
1 stop9h 10m
Southwest
Deal found 8/1![Southwest logo]()
$287
This Delta deal was found by Cheapflights users on 8/1. 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.
Thu 10/17:00 am
ORD
- SEA
Nonstop4h 35m
Delta
Tue 10/610:39 am
SEA
- ORD
Nonstop4h 14m
Delta
Deal found 8/1![Delta logo]()
$287
This Super.com deal was found by Cheapflights users on 7/30. 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 9/91:21 pm
ORD
- SEA
1 stop22h 21m
Frontier
Sun 9/139:45 pm
SEA
- ORD
1 stop29h 53m
Frontier
Deal found 7/30![Frontier logo]()
$288
This Kiwi.com deal was found by Cheapflights users on 7/31. 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 8/262:41 pm
ORD
- SEA
1 stop20h 38m
Frontier
Thu 9/104:27 pm
SEA
- ORD
1 stop29h 56m
Frontier
Deal found 7/31![Frontier logo]()
$289
This Frontier deal was found by Cheapflights users on 7/29. 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 9/118:55 pm
ORD
- SEA
1 stop14h 47m
Frontier
Mon 9/217:45 pm
SEA
- ORD
1 stop7h 53m
Frontier
Deal found 7/29![Frontier logo]()
$290
This Kiwi.com deal was found by Cheapflights users on 7/29. 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.
Sat 8/222:41 pm
ORD
- SEA
1 stop20h 38m
Frontier
Tue 8/252:37 pm
SEA
- ORD
2 stops15h 16m
Frontier
Deal found 7/29![Frontier logo]()
$291
This Southwest deal was found by Cheapflights users on 7/31. 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 9/1511:10 am
MDW
- SEA
2 stops9h 00m
Southwest
Tue 9/2211:05 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Deal found 7/31![Southwest logo]()
$292
This Kissandfly.com deal was found by Cheapflights users on 7/29. 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 Kissandfly.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/292:41 pm
ORD
- SEA
1 stop20h 38m
Multiple Airlines
Fri 9/412:16 am
SEA
- ORD
Nonstop4h 04m
Multiple Airlines
Deal found 7/29![Multiple Airlines logo]()
$292
This Frontier deal was found by Cheapflights users on 7/30. 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 10/236:50 am
ORD
- SEA
1 stop12h 55m
Frontier
Mon 10/267:41 pm
SEA
- ORD
1 stop12h 20m
Frontier
Deal found 7/30![Frontier logo]()
$293
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 August 1, 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 August 1, 2026.
This United Airlines deal was found by Cheapflights users on 8/1. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/113:35 pm
PIA
- SEA
1 stop9h 10m
United Airlines
Sat 9/1911:00 pm
SEA
- PIA
1 stop8h 57m
United Airlines
Deal found 8/1![United Airlines logo]()
$281
This Southwest deal was found by Cheapflights users on 7/31. 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 9/93:05 pm
MDW
- SEA
1 stop7h 55m
Southwest
Sat 9/125:30 pm
SEA
- MDW
1 stop9h 00m
Southwest
Deal found 7/31![Southwest logo]()
$297
This Alaska Airlines deal was found by Cheapflights users on 7/31. 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 10/219:00 am
ORD
- SEA
Nonstop4h 44m
Alaska Airlines
Fri 10/2310:33 am
SEA
- ORD
Nonstop4h 17m
Alaska Airlines
Deal found 7/31![Alaska Airlines logo]()
$307
This Delta deal was found by Cheapflights users on 8/1. 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.
Thu 9/105:44 pm
ORD
- SEA
Nonstop4h 36m
Delta
Fri 9/185:50 pm
SEA
- ORD
Nonstop4h 07m
Delta
Deal found 8/1![Delta logo]()
$317
This American Airlines deal was found by Cheapflights users on 7/29. 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 9/252:41 pm
CMI
- SEA
1 stop9h 11m
American Airlines
Wed 9/3010:59 am
SEA
- CMI
1 stop7h 57m
American Airlines
Deal found 7/29![American Airlines logo]()
$348
This Southwest deal was found by Cheapflights users on 7/30. 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 8/294:05 pm
MDW
- SEA
1 stop8h 50m
Southwest
Sat 9/511:00 pm
SEA
- MDW
1 stop6h 40m
Southwest
Deal found 7/30![Southwest logo]()
$297
This Alaska Airlines deal was found by Cheapflights users on 8/1. 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 9/246:00 am
ORD
- SEA
Nonstop4h 30m
Alaska Airlines
Mon 9/288:41 am
SEA
- ORD
1 stop8h 40m
Alaska Airlines
Deal found 8/1![Alaska Airlines logo]()
$307
This Southwest deal was found by Cheapflights users on 8/1. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/294:05 pm
MDW
- SEA
1 stop8h 50m
Southwest
Tue 9/111:40 am
SEA
- MDW
1 stop9h 40m
Southwest
Deal found 8/1![Southwest logo]()
$297
This United Airlines deal was found by Cheapflights users on 7/30. 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 8/301:30 pm
ORD
- SEA
Nonstop4h 37m
United Airlines
Tue 9/111:00 pm
SEA
- ORD
Nonstop4h 06m
United Airlines
Deal found 7/30![United Airlines logo]()
$347
This Delta deal was found by Cheapflights users on 7/28. 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 10/215:30 pm
ORD
- SEA
Nonstop4h 46m
Delta
Fri 10/235:30 pm
SEA
- ORD
Nonstop4h 04m
Delta
Deal found 7/28![Delta logo]()
$347
This Alaska Airlines deal was found by Cheapflights users on 7/31. 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 9/103:52 pm
ORD
- SEA
Nonstop4h 33m
Alaska Airlines
Sun 9/206:00 am
SEA
- ORD
Nonstop4h 07m
Alaska Airlines
Deal found 7/31![Alaska Airlines logo]()
$317
This Southwest deal was found by Cheapflights users on 8/1. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/179:20 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Mon 9/215:15 am
SEA
- MDW
Nonstop4h 00m
Southwest
Deal found 8/1![Southwest logo]()
$297
This American Airlines deal was found by Cheapflights users on 7/31. 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 10/246:00 am
BMI
- SEA
1 stop9h 36m
American Airlines
Mon 10/2612:04 pm
SEA
- BMI
1 stop8h 54m
American Airlines
Deal found 7/31![American Airlines logo]()
$366
This Delta deal was found by Cheapflights users on 7/28. 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 8/295:56 pm
ORD
- SEA
Nonstop4h 39m
Delta
Sat 9/57:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Deal found 7/28![Delta logo]()
$357
This United Airlines deal was found by Cheapflights users on 8/1. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/28:00 am
STL
- SEA
2 stops13h 08m
United Airlines
Tue 9/810:58 pm
SEA
- STL
1 stop10h 18m
United Airlines
Deal found 8/1![United Airlines logo]()
$362
This Southwest deal was found by Cheapflights users on 8/1. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 9/268:00 am
MDW
- SEA
2 stops10h 50m
Southwest
Sat 10/310:55 am
SEA
- MDW
1 stop8h 00m
Southwest
Deal found 8/1![Southwest logo]()
$302
This American Airlines deal was found by Cheapflights users on 7/31. 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 8/296:36 pm
CMI
- SEA
1 stop7h 37m
American Airlines
Thu 9/35:00 am
SEA
- CMI
1 stop7h 15m
American Airlines
Deal found 7/31![American Airlines logo]()
$368
This Alaska Airlines deal was found by Cheapflights users on 7/31. 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 9/237:00 pm
ORD
- SEA
Nonstop4h 38m
Alaska Airlines
Sun 9/278:41 am
SEA
- ORD
1 stop8h 40m
Alaska Airlines
Deal found 7/31![Alaska Airlines logo]()
$347
This Delta deal was found by Cheapflights users on 7/31. 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 8/264:24 pm
BMI
- SEA
1 stop9h 33m
Delta
Thu 9/311:56 am
SEA
- BMI
1 stop9h 20m
Delta
Deal found 7/31![Delta logo]()
$359
This United Airlines deal was found by Cheapflights users on 7/31. 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 10/288:50 am
STL
- SEA
2 stops9h 37m
United Airlines
Mon 11/210:40 am
SEA
- STL
1 stop9h 35m
United Airlines
Deal found 7/31![United Airlines logo]()
$362
This Southwest deal was found by Cheapflights users on 8/1. 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/510:00 pm
MDW
- SEA
Nonstop4h 40m
Southwest
Mon 11/98:30 am
SEA
- MDW
2 stops10h 00m
Southwest
Deal found 8/1![Southwest logo]()
$312
This American Airlines deal was found by Cheapflights users on 8/1. 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 8/265:00 am
BMI
- SEA
1 stop6h 29m
American Airlines
Thu 9/33:35 pm
SEA
- BMI
1 stop6h 24m
American Airlines
Deal found 8/1![American Airlines logo]()
$379
This Alaska Airlines deal was found by Cheapflights users on 7/31. 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 9/166:08 pm
STL
- SEA
1 stop6h 31m
Alaska Airlines
Sat 9/198:13 am
SEA
- STL
Nonstop4h 08m
Alaska Airlines
Deal found 7/31![Alaska Airlines logo]()
$347
This United Airlines deal was found by Cheapflights users on 7/29. 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 9/228:00 am
STL
- SEA
2 stops13h 08m
United Airlines
Tue 10/137:11 am
SEA
- STL
1 stop9h 32m
United Airlines
Deal found 7/29![United Airlines logo]()
$362
This Delta deal was found by Cheapflights users on 7/31. 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 10/224:26 pm
BMI
- SEA
1 stop9h 26m
Delta
Mon 10/2611:10 pm
SEA
- BMI
2 stops10h 16m
Delta
Deal found 7/31![Delta logo]()
$364
This Alaska Airlines deal was found by Cheapflights users on 7/29. 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 9/83:19 pm
STL
- SEA
Nonstop4h 22m
Alaska Airlines
Tue 9/158:35 am
SEA
- STL
1 stop6h 35m
Alaska Airlines
Deal found 7/29![Alaska Airlines logo]()
$347
This Southwest deal was found by Cheapflights users on 7/28. 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 9/126:25 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Sat 9/1911:05 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Deal found 7/28![Southwest logo]()
$317
This Delta deal was found by Cheapflights users on 8/1. 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.
Fri 10/234:26 pm
BMI
- SEA
1 stop9h 26m
Delta
Mon 10/2611:10 pm
SEA
- BMI
2 stops10h 16m
Delta
Deal found 8/1![Delta logo]()
$364
This American Airlines deal was found by Cheapflights users on 7/30. 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 9/74:54 pm
CMI
- SEA
1 stop9h 05m
American Airlines
Thu 9/171:40 pm
SEA
- CMI
1 stop7h 57m
American Airlines
Deal found 7/30![American Airlines logo]()
$403
This United Airlines deal was found by Cheapflights users on 7/29. 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 8/277:59 pm
ORD
- SEA
Nonstop4h 44m
United Airlines
Sun 8/3011:00 pm
SEA
- ORD
Nonstop4h 06m
United Airlines
Deal found 7/29![United Airlines logo]()
$367
Last-minute flights from Illinois to SeattleDiscover last-minute flight deals from Illinois to Seattle. Data last updated August 1, 2026 and is based on user searches.
Discover last-minute flight deals from Illinois to Seattle. Data last updated August 1, 2026 and is based on user searches.
This Frontier deal was found by Cheapflights users on 7/28. 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 8/79:57 pm
ORD
- SEA
1 stop13h 07m
Frontier
Wed 8/128:13 pm
SEA
- ORD
1 stop7h 24m
Frontier
Deal found 7/28![Frontier logo]()
$288
This CheapOair deal was found by Cheapflights users on 7/30. 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 8/129:57 pm
ORD
- SEA
1 stop13h 07m
Frontier
Wed 8/2610:34 am
SEA
- ORD
1 stop17h 25m
Frontier
Deal found 7/30![Frontier logo]()
$293
This Kiwi.com deal was found by Cheapflights users on 7/27. 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 8/182:41 pm
ORD
- SEA
1 stop20h 38m
Frontier
Sat 8/227:06 pm
SEA
- ORD
1 stop16h 30m
Frontier
Deal found 7/27![Frontier logo]()
$295
This Kiwi.com deal was found by Cheapflights users on 7/30. 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 8/208:11 pm
ORD
- SEA
1 stop16h 28m
Multiple Airlines
Sat 8/296:00 am
SEA
- ORD
Nonstop4h 07m
Multiple Airlines
Deal found 7/30![Multiple Airlines logo]()
$296
This Kiwi.com deal was found by Cheapflights users on 7/29. 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.
Sat 8/222:41 pm
ORD
- SEA
1 stop20h 38m
Frontier
Tue 8/252:37 pm
SEA
- ORD
2 stops15h 16m
Frontier
Deal found 7/29![Frontier logo]()
$291
This Kiwi.com deal was found by Cheapflights users on 7/31. 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 8/262:41 pm
ORD
- SEA
1 stop20h 38m
Frontier
Thu 9/104:27 pm
SEA
- ORD
1 stop29h 56m
Frontier
Deal found 7/31![Frontier logo]()
$289
This Kiwi.com deal was found by Cheapflights users on 7/30. 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 8/272:41 pm
ORD
- SEA
1 stop20h 38m
Frontier
Tue 9/18:48 pm
SEA
- ORD
2 stops24h 20m
Frontier
Deal found 7/30![Frontier logo]()
$290
This Delta deal was found by Cheapflights users on 7/31. 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 8/277:00 am
ORD
- SEA
Nonstop4h 37m
Delta
Mon 8/315:35 pm
SEA
- ORD
Nonstop3h 54m
Delta
Deal found 7/31![Delta logo]()
$297
This Delta deal was found by Cheapflights users on 7/31. 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 8/2912:54 pm
ORD
- SEA
Nonstop4h 46m
Delta
Mon 8/315:35 pm
SEA
- ORD
Nonstop3h 54m
Delta
Deal found 7/31![Delta logo]()
$287
This Kissandfly.com deal was found by Cheapflights users on 7/29. 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 Kissandfly.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/292:41 pm
ORD
- SEA
1 stop20h 38m
Multiple Airlines
Fri 9/412:16 am
SEA
- ORD
Nonstop4h 04m
Multiple Airlines
Deal found 7/29![Multiple Airlines logo]()
$292
This Frontier deal was found by Cheapflights users on 7/29. 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.
Sat 8/292:41 pm
ORD
- SEA
1 stop20h 38m
Frontier
Sat 9/57:06 pm
SEA
- ORD
1 stop16h 30m
Frontier
Deal found 7/29![Frontier logo]()
$294
This Southwest deal was found by Cheapflights users on 7/31. 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 8/295:40 am
MDW
- SEA
1 stop7h 35m
Southwest
Sat 9/511:00 pm
SEA
- MDW
1 stop6h 40m
Southwest
Deal found 7/31![Southwest logo]()
$297
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 August 1, 2026.
Search for one-way flight options from Illinois to Seattle. Find affordable one-way fares based on user searches. Data last updated August 1, 2026.
This Southwest deal was found by Cheapflights users on 7/29. 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 9/156:30 pm
STL
- SEA
1 stop6h 40m
Southwest
Deal found 7/29![Southwest logo]()
$69
This Southwest deal was found by Cheapflights users on 7/29. 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 9/163:45 pm
STL
- SEA
1 stop9h 55m
Southwest
Deal found 7/29![Southwest logo]()
$74
This Southwest deal was found by Cheapflights users on 7/28. 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.
Sun 9/2710:55 am
STL
- SEA
Nonstop4h 20m
Southwest
Deal found 7/28![Southwest logo]()
$79
This Delta deal was found by Cheapflights users on 7/29. 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 9/256:55 pm
STL
- SEA
1 stop7h 04m
Delta
Deal found 7/29![Delta logo]()
$89
This Delta deal was found by Cheapflights users on 7/31. 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 9/285:47 pm
STL
- SEA
1 stop8h 08m
Delta
Deal found 7/31![Delta logo]()
$94
This Kiwi.com deal was found by Cheapflights users on 7/29. 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.
Sun 8/237:58 pm
STL
- SEA
1 stop15h 21m
Frontier
Deal found 7/29![Frontier logo]()
$96
This Kiwi.com deal was found by Cheapflights users on 7/30. 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 8/247:58 pm
STL
- SEA
1 stop15h 21m
Frontier
Deal found 7/30![Frontier logo]()
$97
This Trip.com deal was found by Cheapflights users on 7/28. 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 8/178:08 pm
STL
- SEA
1 stop15h 11m
Frontier
Deal found 7/28![Frontier logo]()
$99
This Southwest deal was found by Cheapflights users on 7/29. 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 10/292:30 pm
STL
- SEA
2 stops12h 05m
Southwest
Deal found 7/29![Southwest logo]()
$100
This Delta deal was found by Cheapflights users on 7/31. 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.
Sun 8/307:45 pm
STL
- SEA
1 stop6h 14m
Delta
Deal found 7/31![Delta logo]()
$104
This American Airlines deal was found by Cheapflights users on 7/31. 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 9/115:28 pm
PIA
- SEA
1 stop8h 43m
American Airlines
Deal found 7/31![American Airlines logo]()
$141
This Southwest deal was found by Cheapflights users on 7/31. 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 8/291:15 pm
MDW
- SEA
1 stop7h 40m
Southwest
Deal found 7/31![Southwest logo]()
$149
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 August 1, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $281 (United Airlines) |
One-way from | $69 (Southwest) |
Popular in | June |
Cheapest in | January |
Average price | $361 |
Good round-trip deal | $303 or less |
Good one-way deal | $206 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 August 1, 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
PeoriaSeattle
PIA - SEA
PIASEA
Greater Peoria
Fri 9/11
3:35 pm-10:45 pm
1 stop9h 10m
Seattle/Tacoma Intl
Sat 9/19
11:00 pm-9:57 am
1 stop8h 57m
$281
ChicagoSeattle
MDW - SEA
MDWSEA
Chicago Midway
Wed 9/9
3:05 pm-9:00 pm
1 stop7h 55m
Seattle/Tacoma Intl
Sat 9/12
5:30 pm-4:30 am
1 stop9h 00m
$297
ChicagoSeattle
MDW - SEA
MDWSEA
Chicago Midway
Sat 8/29
4:05 pm-10:55 pm
1 stop8h 50m
Seattle/Tacoma Intl
Sat 9/5
11:00 pm-7:40 am
1 stop6h 40m
$297
ChicagoSeattle
MDW - SEA
MDWSEA
Chicago Midway
Sat 8/29
4:05 pm-10:55 pm
1 stop8h 50m
Seattle/Tacoma Intl
Tue 9/1
11:40 am-11:20 pm
1 stop9h 40m
$297
ChicagoSeattle
MDW - SEA
MDWSEA
Chicago Midway
Thu 9/17
9:20 pm-11:55 pm
Nonstop4h 35m
Seattle/Tacoma Intl
Mon 9/21
5:15 am-11:15 am
Nonstop4h 00m
$297
ChicagoSeattle
MDW - SEA
MDWSEA
Chicago Midway
Sat 9/26
8:00 am-4:50 pm
2 stops10h 50m
Seattle/Tacoma Intl
Sat 10/3
10:55 am-8:55 pm
1 stop8h 00m
$302
ChicagoSeattle
ORD - SEA
ORDSEA
Chicago O'Hare Intl
Wed 10/21
9:00 am-11:44 am
Nonstop4h 44m
Seattle/Tacoma Intl
Fri 10/23
10:33 am-4:50 pm
Nonstop4h 17m
$307
ChicagoSeattle
ORD - SEA
ORDSEA
Chicago O'Hare Intl
Thu 9/24
6:00 am-8:30 am
Nonstop4h 30m
Seattle/Tacoma Intl
Mon 9/28
8:41 am-7:21 pm
1 stop8h 40m
$307
ChicagoSeattle
MDW - SEA
MDWSEA
Chicago Midway
Thu 11/5
10:00 pm-12:40 am
Nonstop4h 40m
Seattle/Tacoma Intl
Mon 11/9
8:30 am-8:30 pm
2 stops10h 00m
$312
ChicagoSeattle
ORD - SEA
ORDSEA
Chicago O'Hare Intl
Thu 9/10
5:44 pm-8:20 pm
Nonstop4h 36m
Seattle/Tacoma Intl
Fri 9/18
5:50 pm-11:57 pm
Nonstop4h 07m
$317
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
PIA-SEA
MDW-SEA
ORD-SEA
CMI-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
PIA-SEA
MDW-SEA
ORD-SEA
What is the cheapest month to book a flight from Illinois to Seattle?
Currently, January is the cheapest month in which you can book a flight from Illinois to Seattle (average of $237). Flying from Illinois to Seattle in July is currently the most expensive (average of $415). 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 August 1, 2026.
One of the essential ways to save on airfare from Illinois to Seattle is to remain as flexible as possible. Flights that are at noon tend to be the most expensive. A flight in the evening could potentially save you up to 26% on airfare.
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 August 1, 2026.
The most flights from USIL to SEA are scheduled on a Friday (60 on average). You will have fewer flight options on Wednesday, which is when the least amount of flights are scheduled (7 on average).
How much does it cost to fly round-trip from Illinois to Seattle?
Airfare is below average for this route at the moment.
Illinois to Seattle flights typically cost between $295 and $437 in October.The cheapest round-trip price found within the last 5 days was $287 on Delta (Oct 1-Oct 6).
How far ahead should I book a flight from Illinois to Seattle?
The price you pay for your flight from Illinois to Seattle may vary depending on when you book. For the best chance of a lower fare, look to book 34 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 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 July 25, 2026.
Travelers seeking maximum savings on their Illinois to Seattle flight should consider departing on Sunday mornings when fares are most often at their lowest. Sunday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.
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
Renton
Tacoma
Lacey
Leavenworth
Olympia
Edmonds
Tukwila
Snoqualmie
Tumwater
Centralia
Puyallup
Kent
Ellensburg
Fife
Marysville
Ocean Shores
Lakewood
Lynnwood
Shoreline
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Alternative routes for Illinois to Seattle
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Complete your trip
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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 August 1, 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 August 1, 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 August 1, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$62 | Average$249 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$131 | Average$265 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$151 | Average$343 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$177 | Average$355 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$178 | Average$490 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$180 | Average$452 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$227 | Average$371 | FlexibilityNo cancel fee | On-time63% |