$94+ 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 9/23. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Aug 15 — Aug 221
Round-trip
1 adult, Economy
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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 July 16, 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 July 16, 2026.
This Kiwi.com deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 8/177:06 pm
SEA
- ORD
1 stop16h 30m
Multiple Airlines
Thu 8/202:18 pm
ORD
- SEA
1 stop9h 22m
Multiple Airlines
Deal found 7/14![Multiple Airlines logo]()
$310
This American Airlines deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 9/113:41 pm
SEA
- PIA
1 stop6h 27m
American Airlines
Wed 9/165:28 pm
PIA
- SEA
1 stop8h 43m
American Airlines
Deal found 7/15![American Airlines logo]()
$310
This Kiwi.com deal was found by Cheapflights users on 7/13. Clicking the “Pick Dates” 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 8/1210:29 am
SEA
- ORD
Nonstop4h 15m
Multiple Airlines
Wed 8/192:41 pm
ORD
- SEA
1 stop20h 38m
Multiple Airlines
Deal found 7/13![Multiple Airlines logo]()
$311
This Southwest deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 8/295:30 am
SEA
- MDW
1 stop6h 40m
Southwest
Sun 9/64:00 pm
MDW
- SEA
2 stops8h 55m
Southwest
Deal found 7/14![Southwest logo]()
$311
This CheapOair deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/47:06 pm
SEA
- ORD
1 stop16h 30m
Frontier
Mon 9/78:11 pm
ORD
- SEA
1 stop16h 28m
Frontier
Deal found 7/15![Frontier logo]()
$312
This Southwest deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 8/293:35 pm
SEA
- MDW
2 stops12h 10m
Southwest
Sat 9/52:15 pm
MDW
- SEA
2 stops9h 15m
Southwest
Deal found 7/15![Southwest logo]()
$312
This Mytrip deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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.
Wed 8/1212:17 am
SEA
- ORD
Nonstop4h 03m
Multiple Airlines
Mon 8/242:41 pm
ORD
- SEA
1 stop24h 41m
Multiple Airlines
Deal found 7/14![Multiple Airlines logo]()
$313
This Southwest deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 8/145:50 pm
SEA
- MDW
1 stop8h 40m
Southwest
Mon 8/179:20 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 7/14![Southwest logo]()
$313
This Kiwi.com deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 8/118:13 pm
SEA
- ORD
1 stop7h 24m
Frontier
Sat 8/222:41 pm
ORD
- SEA
1 stop20h 38m
Frontier
Deal found 7/15![Frontier logo]()
$314
This Southwest deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 8/315:50 pm
SEA
- MDW
1 stop8h 40m
Southwest
Sat 9/52:15 pm
MDW
- SEA
2 stops9h 15m
Southwest
Deal found 7/15![Southwest logo]()
$314
This Kiwi.com deal was found by Cheapflights users on 7/13. Clicking the “Pick Dates” 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 8/296:00 am
SEA
- ORD
Nonstop4h 07m
Multiple Airlines
Wed 9/911:06 am
ORD
- SEA
1 stop15h 21m
Multiple Airlines
Deal found 7/13![Multiple Airlines logo]()
$315
This Southwest deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 10/97:40 am
SEA
- MDW
2 stops10h 55m
Southwest
Tue 10/136:05 am
MDW
- SEA
1 stop8h 00m
Southwest
Deal found 7/15![Southwest logo]()
$315
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 July 16, 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 July 16, 2026.
This Southwest deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 8/271:30 pm
SEA
- MDW
1 stop7h 50m
Southwest
Mon 8/315:00 pm
MDW
- SEA
2 stops7h 55m
Southwest
Deal found 7/15![Southwest logo]()
$314
This Kiwi.com deal was found by Cheapflights users on 7/12. Clicking the “Pick Dates” 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 8/267:06 pm
SEA
- RFD
2 stops18h 03m
Multiple Airlines
Sun 8/309:35 pm
RFD
- SEA
1 stop15h 04m
Multiple Airlines
Deal found 7/12![Multiple Airlines logo]()
$317
This American Airlines deal was found by Cheapflights users on 7/16. Clicking the “Pick Dates” 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 9/2910:59 am
SEA
- CMI
1 stop7h 57m
American Airlines
Wed 9/301:23 pm
CMI
- SEA
1 stop10h 13m
American Airlines
Deal found 7/16![American Airlines logo]()
$338
This Delta deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 8/276:00 am
SEA
- MLI
1 stop8h 25m
Delta
Sun 8/3011:08 am
MLI
- SEA
1 stop9h 57m
Delta
Deal found 7/14![Delta logo]()
$349
This Alaska Airlines deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 9/306:00 am
SEA
- ORD
Nonstop4h 07m
Alaska Airlines
Sat 10/37:16 pm
ORD
- SEA
Nonstop4h 43m
Alaska Airlines
Deal found 7/14![Alaska Airlines logo]()
$357
This United Airlines deal was found by Cheapflights users on 7/13. Clicking the “Pick Dates” 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 8/185:13 pm
SEA
- ORD
Nonstop4h 04m
United Airlines
Fri 8/217:00 am
ORD
- SEA
Nonstop4h 35m
United Airlines
Deal found 7/13![United Airlines logo]()
$368
This Southwest deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 9/107:00 am
SEA
- MDW
2 stops8h 10m
Southwest
Thu 9/106:15 pm
MDW
- SEA
1 stop8h 25m
Southwest
Deal found 7/15![Southwest logo]()
$314
This American Airlines deal was found by Cheapflights users on 7/11. Clicking the “Pick Dates” 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 8/2610:15 am
SEA
- MLI
1 stop9h 56m
American Airlines
Sat 8/294:32 pm
MLI
- SEA
1 stop7h 54m
American Airlines
Deal found 7/11![American Airlines logo]()
$349
This Delta deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 10/75:53 pm
SEA
- ORD
Nonstop4h 04m
Delta
Wed 10/145:59 pm
ORD
- SEA
Nonstop4h 46m
Delta
Deal found 7/14![Delta logo]()
$357
This Alaska Airlines deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 9/67:40 am
SEA
- ORD
1 stop9h 41m
Alaska Airlines
Tue 9/87:20 am
ORD
- SEA
2 stops12h 19m
Alaska Airlines
Deal found 7/15![Alaska Airlines logo]()
$365
This Kiwi.com deal was found by Cheapflights users on 7/13. Clicking the “Pick Dates” 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 10/811:06 am
SEA
- RFD
2 stops22h 21m
Multiple Airlines
Sun 10/119:33 pm
RFD
- SEA
1 stop14h 27m
Multiple Airlines
Deal found 7/13![Multiple Airlines logo]()
$376
This United Airlines deal was found by Cheapflights users on 7/12. Clicking the “Pick Dates” 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 9/1111:00 pm
SEA
- PIA
1 stop8h 57m
United Airlines
Wed 9/168:29 am
PIA
- SEA
2 stops15h 22m
United Airlines
Deal found 7/12![United Airlines logo]()
$376
This American Airlines deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 10/23:41 pm
SEA
- MLI
1 stop6h 24m
American Airlines
Sun 10/44:57 pm
MLI
- SEA
1 stop9h 14m
American Airlines
Deal found 7/15![American Airlines logo]()
$349
This Delta deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 9/210:50 am
SEA
- ORD
Nonstop4h 10m
Delta
Wed 9/97:00 am
ORD
- SEA
Nonstop4h 35m
Delta
Deal found 7/14![Delta logo]()
$357
This Southwest deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 9/1010:50 am
SEA
- MDW
Nonstop4h 05m
Southwest
Mon 9/149:20 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 7/14![Southwest logo]()
$357
This Alaska Airlines deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/2612:16 am
SEA
- ORD
Nonstop4h 04m
Alaska Airlines
Sun 8/306:00 am
ORD
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 7/15![Alaska Airlines logo]()
$368
This Kiwi.com deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 8/158:13 pm
SEA
- RFD
1 stop14h 21m
Multiple Airlines
Sun 8/239:35 pm
RFD
- SEA
1 stop15h 04m
Multiple Airlines
Deal found 7/14![Multiple Airlines logo]()
$382
This Delta deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 9/1011:45 am
SEA
- ORD
Nonstop4h 16m
Delta
Mon 9/1412:50 pm
ORD
- SEA
Nonstop4h 35m
Delta
Deal found 7/14![Delta logo]()
$357
This Southwest deal was found by Cheapflights users on 7/13. Clicking the “Pick Dates” 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 9/211:05 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Sat 9/126:25 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 7/13![Southwest logo]()
$357
This United Airlines deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/611:05 am
SEA
- STL
1 stop7h 31m
United Airlines
Wed 10/78:00 am
STL
- SEA
2 stops14h 37m
United Airlines
Deal found 7/14![United Airlines logo]()
$412
This Alaska Airlines deal was found by Cheapflights users on 7/16. Clicking the “Pick Dates” 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.
Fri 8/216:00 am
SEA
- ORD
Nonstop4h 07m
Alaska Airlines
Tue 8/256:00 am
ORD
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 7/16![Alaska Airlines logo]()
$376
This Delta deal was found by Cheapflights users on 7/13. Clicking the “Pick Dates” 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 9/57:15 am
SEA
- ORD
Nonstop4h 08m
Delta
Tue 9/1512:50 pm
ORD
- SEA
Nonstop4h 35m
Delta
Deal found 7/13![Delta logo]()
$357
This Southwest deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/288:15 pm
SEA
- MDW
1 stop7h 30m
Southwest
Tue 8/186:00 pm
MDW
- SEA
1 stop7h 05m
Southwest
Deal found 7/15![Southwest logo]()
$360
This Alaska Airlines deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 8/109:28 pm
SEA
- ORD
1 stop5h 32m
Alaska Airlines
Sun 8/168:20 pm
ORD
- SEA
Nonstop4h 44m
Alaska Airlines
Deal found 7/15![Alaska Airlines logo]()
$377
This Kiwi.com deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 9/12:37 pm
SEA
- RFD
2 stops20h 42m
Multiple Airlines
Thu 9/39:29 pm
RFD
- SEA
1 stop15h 10m
Multiple Airlines
Deal found 7/15![Multiple Airlines logo]()
$419
This Delta deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 8/269:53 am
SEA
- MLI
2 stops10h 26m
Delta
Sat 8/2911:08 am
MLI
- SEA
2 stops12h 57m
Delta
Deal found 7/14![Delta logo]()
$359
This American Airlines deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 8/1211:56 pm
SEA
- CMI
1 stop9h 15m
American Airlines
Tue 8/184:54 pm
CMI
- SEA
1 stop9h 05m
American Airlines
Deal found 7/15![American Airlines logo]()
$438
This United Airlines deal was found by Cheapflights users on 7/11. Clicking the “Pick Dates” 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 12/810:40 pm
SEA
- BMI
1 stop8h 17m
United Airlines
Sat 12/126:00 am
BMI
- SEA
1 stop7h 40m
United Airlines
Deal found 7/11![United Airlines logo]()
$443
This Southwest deal was found by Cheapflights users on 7/12. Clicking the “Pick Dates” 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 8/1211:05 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Sat 8/1510:05 am
MDW
- SEA
1 stop8h 45m
Southwest
Deal found 7/12![Southwest logo]()
$367
This Alaska Airlines deal was found by Cheapflights users on 7/12. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/227:40 am
SEA
- ORD
1 stop9h 41m
Alaska Airlines
Sun 8/306:00 am
ORD
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 7/12![Alaska Airlines logo]()
$378
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated July 16, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated July 16, 2026 and is based on user searches.
This Kiwi.com deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/2312:17 am
SEA
- ORD
Nonstop4h 03m
Multiple Airlines
Mon 8/109:57 pm
ORD
- SEA
1 stop13h 07m
Multiple Airlines
Deal found 7/14![Multiple Airlines logo]()
$311
This Kiwi.com deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 7/258:13 pm
SEA
- ORD
1 stop7h 24m
Frontier
Wed 7/299:57 pm
ORD
- SEA
1 stop13h 20m
Frontier
Deal found 7/14![Frontier logo]()
$316
This Southwest deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 8/145:50 pm
SEA
- MDW
1 stop8h 40m
Southwest
Mon 8/179:20 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 7/14![Southwest logo]()
$313
This Southwest deal was found by Cheapflights users on 7/16. Clicking the “Pick Dates” 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 8/206:15 am
SEA
- MDW
2 stops9h 05m
Southwest
Mon 8/245:00 pm
MDW
- SEA
2 stops7h 55m
Southwest
Deal found 7/16![Southwest logo]()
$319
This Southwest deal was found by Cheapflights users on 7/16. Clicking the “Pick Dates” 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 8/216:15 am
SEA
- MDW
2 stops9h 05m
Southwest
Mon 8/249:20 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 7/16![Southwest logo]()
$318
This Kiwi.com deal was found by Cheapflights users on 7/12. Clicking the “Pick Dates” 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 8/228:53 pm
SEA
- RFD
1 stop21h 52m
Multiple Airlines
Sun 8/309:35 pm
RFD
- SEA
1 stop15h 04m
Multiple Airlines
Deal found 7/12![Multiple Airlines logo]()
$321
This Southwest deal was found by Cheapflights users on 7/16. Clicking the “Pick Dates” 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 8/267:10 am
SEA
- MDW
2 stops9h 50m
Southwest
Fri 8/284:55 pm
MDW
- SEA
1 stop9h 45m
Southwest
Deal found 7/16![Southwest logo]()
$315
This Kiwi.com deal was found by Cheapflights users on 7/12. Clicking the “Pick Dates” 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 8/267:06 pm
SEA
- RFD
2 stops18h 03m
Multiple Airlines
Sun 8/309:35 pm
RFD
- SEA
1 stop15h 04m
Multiple Airlines
Deal found 7/12![Multiple Airlines logo]()
$317
This Southwest deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 8/295:30 am
SEA
- MDW
1 stop6h 40m
Southwest
Sun 9/64:00 pm
MDW
- SEA
2 stops8h 55m
Southwest
Deal found 7/14![Southwest logo]()
$311
This Southwest deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 8/293:35 pm
SEA
- MDW
2 stops12h 10m
Southwest
Sat 9/52:15 pm
MDW
- SEA
2 stops9h 15m
Southwest
Deal found 7/15![Southwest logo]()
$312
This Southwest deal was found by Cheapflights users on 7/16. Clicking the “Pick Dates” 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 8/305:40 am
SEA
- MDW
Nonstop3h 55m
Southwest
Sun 9/68:30 pm
MDW
- SEA
Nonstop4h 35m
Southwest
Deal found 7/16![Southwest logo]()
$317
This Southwest deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 8/3110:30 pm
SEA
- MDW
1 stop8h 30m
Southwest
Sat 9/52:15 pm
MDW
- SEA
2 stops9h 15m
Southwest
Deal found 7/15![Southwest logo]()
$314
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 July 16, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated July 16, 2026.
This Delta deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 10/149:43 am
SEA
- STL
1 stop5h 51m
Delta
Deal found 7/14![Delta logo]()
$94
This Southwest deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 8/225:00 am
SEA
- STL
1 stop13h 20m
Southwest
Deal found 7/14![Southwest logo]()
$99
This Delta deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 10/1211:50 pm
SEA
- STL
1 stop7h 13m
Delta
Deal found 7/14![Delta logo]()
$104
This Southwest deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 10/128:40 pm
SEA
- STL
1 stop13h 00m
Southwest
Deal found 7/14![Southwest logo]()
$109
This Kiwi.com deal was found by Cheapflights users on 7/16. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/28:53 pm
SEA
- MLI
1 stop13h 30m
Multiple Airlines
Deal found 7/16![Multiple Airlines logo]()
$116
This Trip.com deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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.
Wed 8/127:06 pm
SEA
- STL
1 stop22h 17m
Frontier
Deal found 7/14![Frontier logo]()
$119
This Kiwi.com deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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 10/147:41 pm
SEA
- STL
1 stop21h 34m
Frontier
Deal found 7/14![Frontier logo]()
$125
This Kiwi.com deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 10/129:16 pm
SEA
- STL
2 stops19h 59m
Frontier
Deal found 7/15![Frontier logo]()
$126
This Kiwi.com deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 10/139:16 pm
SEA
- STL
2 stops19h 59m
Frontier
Deal found 7/15![Frontier logo]()
$127
This Super.com deal was found by Cheapflights users on 7/14. Clicking the “Pick Dates” 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.
Sat 9/129:16 pm
SEA
- STL
1 stop12h 35m
Frontier
Deal found 7/14![Frontier logo]()
$136
This Kiwi.com deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 8/2010:34 am
SEA
- ORD
1 stop17h 25m
Frontier
Deal found 7/15![Frontier logo]()
$153
This Southwest deal was found by Cheapflights users on 7/15. Clicking the “Pick Dates” 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 8/223:35 pm
SEA
- MDW
2 stops12h 10m
Southwest
Deal found 7/15![Southwest logo]()
$153
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 July 16, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $259 (Kiwi.com) |
One-way from | $94 (Delta) |
Popular in | June |
Cheapest in | February |
Average price | $383 |
Good round-trip deal | $383 or less |
Good one-way deal | $208 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 July 16, 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
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Thu 8/27
1:30 pm-11:20 pm
1 stop7h 50m
Chicago Midway
Mon 8/31
5:00 pm-10:55 pm
2 stops7h 55m
$314
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Thu 9/10
7:00 am-5:10 pm
2 stops8h 10m
Chicago Midway
Thu 9/10
6:15 pm-12:40 am
1 stop8h 25m
$314
SeattleChicago
SEA - RFD
SEARFD
Seattle/Tacoma Intl
Wed 8/26
7:06 pm-3:09 pm
2 stops18h 03m
Chicago Greater Rockford
Sun 8/30
9:35 pm-10:39 am
1 stop15h 04m
$317
SeattleChampaign
SEA - CMI
SEACMI
Seattle/Tacoma Intl
Tue 9/29
10:59 am-8:56 pm
1 stop7h 57m
Champaign University-Willard
Wed 9/30
1:23 pm-9:36 pm
1 stop10h 13m
$338
SeattleMoline
SEA - MLI
SEAMLI
Seattle/Tacoma Intl
Thu 8/27
6:00 am-4:25 pm
1 stop8h 25m
Moline Quad-City
Sun 8/30
11:08 am-7:05 pm
1 stop9h 57m
$349
SeattleMoline
SEA - MLI
SEAMLI
Seattle/Tacoma Intl
Wed 8/26
10:15 am-10:11 pm
1 stop9h 56m
Moline Quad-City
Sat 8/29
4:32 pm-10:26 pm
1 stop7h 54m
$349
SeattleMoline
SEA - MLI
SEAMLI
Seattle/Tacoma Intl
Fri 10/2
3:41 pm-12:05 am
1 stop6h 24m
Moline Quad-City
Sun 10/4
4:57 pm-12:11 am
1 stop9h 14m
$349
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 9/30
6:00 am-12:07 pm
Nonstop4h 07m
Chicago O'Hare Intl
Sat 10/3
7:16 pm-9:59 pm
Nonstop4h 43m
$357
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 10/7
5:53 pm-11:57 pm
Nonstop4h 04m
Chicago O'Hare Intl
Wed 10/14
5:59 pm-8:45 pm
Nonstop4h 46m
$357
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 9/2
10:50 am-5:00 pm
Nonstop4h 10m
Chicago O'Hare Intl
Wed 9/9
7:00 am-9:35 am
Nonstop4h 35m
$357
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-STL
SEA-RFD
SEA-ORD
SEA-MDW
SEA-BMI
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-STL
SEA-RFD
SEA-ORD
SEA-MDW
What is the cheapest month to book a flight from Seattle to Illinois?
Currently, January is the cheapest month in which you can book a flight from Seattle to Illinois (average of $47). Flying from Seattle to Illinois in March is currently the most expensive (average of $677). 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 July 16, 2026.
It’s typically best to fly out from Seattle to Illinois at noon. Doing so could potentially save you 6% on the flight price compared to flying in the morning, which is usually more expensive.
Weekly flight availability from Seattle to Illinois
Explore weekly flight availability from Seattle to Illinois. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated July 16, 2026.
The most flights from SEA to USIL are scheduled on a Tuesday (61 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (33 on average).
How much does it cost to fly round-trip from Seattle to Illinois?
How far ahead should I book a flight from Seattle to Illinois?
The price you pay for your flight from Seattle to Illinois may vary depending on when you book. For the best chance of a lower fare, look to book 81 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.
What is the cheapest day to fly from Seattle to Illinois?
Use this chart to determine the cheapest time to fly round-trip from Seattle to Illinois. Price data was last updated on July 11, 2026.
Travelers seeking maximum savings on their Seattle to Illinois flight should consider departing on Saturday afternoons when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
Reviews of airlines servicing Illinois
Get insights into the airlines that provide service to Illinois. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Illinois. Reviews last updated July 16, 2026.
Read through reviews of airlines operating flights from Seattle to Illinois, such as Southwest,Alaska Airlines, andDelta. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Comfort
8.0
Food
7.0
Overall
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Food
7.0
Overall
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Food
7.0
Overall
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Food
7.0
Overall
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Food
7.0
Overall
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
Comfort
8.0
Food
7.0
Overall
8.0
Boarding
8.1
Crew
8.6
Entertainment
7.5
Reviews
1 / 20
6.0
GoodReza,Jun 2026
TPA - MDW
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 July 16, 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 July 16, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$118 | Average$219 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$124 | Average$355 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$177 | Average$361 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$177 | Average$451 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$180 | Average$430 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$193 | Average$313 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$239 | Average$372 | FlexibilityNo cancel fee | On-time63% |