$82+ 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 4/17. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ORD
Apr 21 — Apr 281
Round-trip
1 adult, Economy
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Find cheap flights from Seattle to Illinois with Cheapflights
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Cheapest flights from Seattle to IllinoisExplore the most affordable flight options available from Seattle to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on March 22, 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 March 22, 2026.
This Gotogate 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/87:50 pm
SEA
- ORD
1 stop22h 47m
Frontier
Sun 5/109:42 pm
ORD
- SEA
1 stop14h 07m
Frontier
Deal found 3/20![Frontier logo]()
$210
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.
Tue 4/2110:57 am
SEA
- ORD
1 stop10h 30m
Multiple Airlines
Tue 5/59:42 pm
ORD
- SEA
1 stop14h 07m
Multiple Airlines
Deal found 3/19![Multiple Airlines logo]()
$211
This Booking.com deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/27:12 pm
SEA
- ORD
1 stop12h 33m
Frontier
Mon 5/47:21 pm
ORD
- SEA
1 stop25h 14m
Frontier
Deal found 3/18![Frontier logo]()
$212
This Expedia 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/158:07 pm
SEA
- ORD
1 stop11h 43m
Multiple Airlines
Wed 4/228:48 pm
ORD
- SEA
Nonstop4h 41m
Multiple Airlines
Deal found 3/21![Multiple Airlines logo]()
$213
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.
Wed 4/158:07 pm
SEA
- ORD
1 stop11h 43m
Frontier
Mon 4/207:56 pm
ORD
- SEA
1 stop23h 46m
Frontier
Deal found 3/20![Frontier logo]()
$216
This Booking.com 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/127:50 pm
SEA
- ORD
1 stop22h 47m
Frontier
Tue 5/198:56 pm
ORD
- SEA
1 stop23h 39m
Frontier
Deal found 3/21![Frontier logo]()
$217
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 4/139:34 pm
SEA
- ORD
1 stop30h 34m
Frontier
Mon 4/2010:55 am
ORD
- SEA
1 stop24h 32m
Frontier
Deal found 3/20![Frontier logo]()
$218
This SmartFares 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 SmartFares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/185:49 pm
SEA
- ORD
Nonstop4h 10m
Alaska Airlines
Fri 4/248:48 pm
ORD
- SEA
Nonstop4h 41m
Alaska Airlines
Deal found 3/19![Alaska Airlines logo]()
$220
This Booking.com deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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.
Mon 5/410:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Mon 5/119:42 pm
ORD
- SEA
1 stop14h 07m
Frontier
Deal found 3/17![Frontier logo]()
$222
This Booking.com 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/2310:57 am
SEA
- ORD
1 stop17h 23m
Frontier
Mon 4/277:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/22![Frontier logo]()
$223
This eDestinos 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 eDestinos is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/2912:29 am
SEA
- ORD
Nonstop4h 11m
Multiple Airlines
Tue 5/59:42 pm
ORD
- SEA
1 stop14h 07m
Multiple Airlines
Deal found 3/19![Multiple Airlines logo]()
$224
This Southwest deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” 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 4/175:15 am
SEA
- MDW
Nonstop3h 55m
Southwest
Thu 4/239:35 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/18![Southwest logo]()
$237
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 March 22, 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 March 22, 2026.
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.
Thu 6/1111:52 pm
SEA
- ORD
Nonstop4h 06m
United Airlines
Sun 6/149:15 pm
ORD
- SEA
Nonstop4h 44m
United Airlines
Deal found 3/20![United Airlines logo]()
$237
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 4/1711:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Fri 4/249:35 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/19![Southwest logo]()
$237
This Alaska 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/185:49 pm
SEA
- ORD
Nonstop4h 10m
Alaska Airlines
Tue 4/218:00 am
ORD
- SEA
Nonstop4h 43m
Alaska Airlines
Deal found 3/19![Alaska Airlines logo]()
$255
This Delta deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” 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 4/1711:10 am
SEA
- ORD
1 stop8h 15m
Delta
Thu 4/231:36 pm
ORD
- SEA
1 stop10h 14m
Delta
Deal found 3/18![Delta logo]()
$257
This American Airlines deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/1610:25 am
SEA
- CMI
1 stop8h 14m
American Airlines
Fri 4/176:58 pm
CMI
- SEA
1 stop7h 38m
American Airlines
Deal found 3/17![American Airlines logo]()
$448
This Southwest deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/211:55 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Sat 5/95:30 pm
MDW
- SEA
1 stop6h 40m
Southwest
Deal found 3/18![Southwest logo]()
$247
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.
Wed 6/248:13 pm
SEA
- RFD
1 stop14h 10m
Multiple Airlines
Mon 6/2910:05 pm
RFD
- SEA
2 stops46h 21m
Multiple Airlines
Deal found 3/20![Multiple Airlines logo]()
$496
This Delta deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/1510:35 am
SEA
- ORD
Nonstop4h 04m
Delta
Wed 4/222:25 pm
ORD
- SEA
1 stop11h 28m
Delta
Deal found 3/17![Delta logo]()
$257
This Southwest deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/156:00 am
SEA
- MDW
Nonstop4h 00m
Southwest
Wed 4/2210:15 am
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/17![Southwest logo]()
$247
This Alaska Airlines deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/95:49 pm
SEA
- ORD
Nonstop4h 10m
Alaska Airlines
Mon 4/136:00 am
ORD
- SEA
Nonstop4h 37m
Alaska Airlines
Deal found 3/17![Alaska Airlines logo]()
$287
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.
Fri 5/82:27 pm
SEA
- ORD
Nonstop4h 11m
United Airlines
Sun 5/109:20 pm
ORD
- SEA
Nonstop4h 39m
United Airlines
Deal found 3/19![United Airlines logo]()
$301
This Southwest deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/2911:45 pm
SEA
- STL
1 stop7h 20m
Southwest
Wed 5/65:30 am
STL
- SEA
2 stops14h 30m
Southwest
Deal found 3/17![Southwest logo]()
$260
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.
Tue 4/147:37 pm
SEA
- ORD
1 stop7h 50m
United Airlines
Fri 4/179:54 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Deal found 3/22![United Airlines logo]()
$315
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.
Wed 4/1511:35 am
SEA
- ORD
2 stops10h 20m
Southwest
Wed 4/227:45 am
ORD
- SEA
1 stop7h 50m
Southwest
Deal found 3/21![Southwest logo]()
$280
This United Airlines deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/912:54 pm
SEA
- ORD
1 stop8h 34m
United Airlines
Fri 4/109:54 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Deal found 3/17![United Airlines logo]()
$318
This Delta deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” 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 4/1711:10 am
SEA
- MDW
1 stop9h 18m
Delta
Thu 4/231:24 pm
MDW
- SEA
1 stop7h 04m
Delta
Deal found 3/18![Delta logo]()
$407
This Alaska 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 Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/315:52 pm
SEA
- STL
Nonstop4h 02m
Alaska Airlines
Mon 6/87:41 pm
STL
- SEA
Nonstop4h 30m
Alaska Airlines
Deal found 3/19![Alaska Airlines logo]()
$407
This United Airlines deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 7/288:30 am
SEA
- STL
2 stops13h 27m
United Airlines
Wed 8/124:40 pm
STL
- SEA
1 stop8h 31m
United Airlines
Deal found 3/17![United Airlines logo]()
$344
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 4/2012:55 pm
SEA
- STL
2 stops9h 35m
Southwest
Sat 4/2510:35 am
STL
- SEA
2 stops9h 20m
Southwest
Deal found 3/21![Southwest logo]()
$319
This American 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 4/121:19 pm
SEA
- CMI
1 stop6h 16m
American Airlines
Thu 4/166:58 pm
CMI
- SEA
1 stop7h 38m
American Airlines
Deal found 3/21![American Airlines logo]()
$495
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 4/25:30 am
SEA
- STL
1 stop5h 47m
Delta
Mon 4/62:12 pm
STL
- SEA
1 stop6h 18m
Delta
Deal found 3/19![Delta logo]()
$424
This United Airlines deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” 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 4/113:48 pm
SEA
- ORD
1 stop6h 41m
United Airlines
Sun 4/129:54 pm
ORD
- SEA
Nonstop4h 40m
United Airlines
Deal found 3/18![United Airlines logo]()
$354
This Alaska Airlines deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/258:30 am
SEA
- MLI
1 stop7h 37m
Alaska Airlines
Wed 4/295:15 am
MLI
- SEA
1 stop7h 25m
Alaska Airlines
Deal found 3/17![Alaska Airlines logo]()
$439
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 4/148:25 am
SEA
- ORD
2 stops13h 30m
Southwest
Mon 4/206:15 am
ORD
- SEA
1 stop9h 55m
Southwest
Deal found 3/19![Southwest logo]()
$346
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.
Thu 4/165:35 am
SEA
- STL
1 stop5h 48m
Delta
Thu 4/166:45 pm
STL
- SEA
1 stop7h 14m
Delta
Deal found 3/21![Delta logo]()
$424
This Kiwi.com deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 7/118:13 pm
SEA
- RFD
1 stop14h 11m
Multiple Airlines
Sun 7/191:14 pm
RFD
- SEA
1 stop23h 21m
Multiple Airlines
Deal found 3/17![Multiple Airlines logo]()
$568
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.
Mon 5/1810:29 pm
SEA
- EVV
1 stop9h 57m
American Airlines
Tue 5/266:32 pm
EVV
- SEA
1 stop7h 44m
American Airlines
Deal found 3/20![American Airlines logo]()
$517
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.
Fri 5/296:26 am
SEA
- MLI
2 stops15h 29m
Alaska Airlines
Wed 6/311:07 am
MLI
- SEA
2 stops14h 11m
Alaska Airlines
Deal found 3/21![Alaska Airlines logo]()
$449
This Southwest deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/311:45 pm
SEA
- MDW
Nonstop4h 00m
Southwest
Mon 6/89:55 pm
MDW
- SEA
Nonstop4h 30m
Southwest
Deal found 3/18![Southwest logo]()
$355
This United Airlines deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/258:45 am
SEA
- PIA
2 stops10h 28m
United Airlines
Tue 4/2810:40 am
PIA
- SEA
2 stops14h 47m
United Airlines
Deal found 3/17![United Airlines logo]()
$391
Last-minute flights from Seattle to IllinoisDiscover last-minute flight deals from Seattle to Illinois. Data last updated March 22, 2026 and is based on user searches.
Discover last-minute flight deals from Seattle to Illinois. Data last updated March 22, 2026 and is based on user searches.
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.
Sat 4/1112:42 pm
SEA
- ORD
1 stop9h 56m
Frontier
Mon 4/208:58 pm
ORD
- SEA
2 stops14h 29m
Frontier
Deal found 3/20![Frontier logo]()
$222
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.
Sat 4/1112:42 pm
SEA
- ORD
1 stop9h 56m
Frontier
Tue 4/143:27 pm
ORD
- SEA
2 stops44h 00m
Frontier
Deal found 3/20![Frontier logo]()
$230
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 4/139:34 pm
SEA
- ORD
1 stop30h 34m
Frontier
Mon 4/2010:55 am
ORD
- SEA
1 stop24h 32m
Frontier
Deal found 3/20![Frontier logo]()
$218
This Mytrip 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/135:59 pm
SEA
- ORD
1 stop9h 40m
Frontier
Thu 4/1610:55 am
ORD
- SEA
1 stop30h 10m
Frontier
Deal found 3/20![Frontier logo]()
$232
This Expedia 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/158:07 pm
SEA
- ORD
1 stop11h 43m
Multiple Airlines
Wed 4/228:48 pm
ORD
- SEA
Nonstop4h 41m
Multiple Airlines
Deal found 3/21![Multiple Airlines logo]()
$213
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.
Wed 4/158:07 pm
SEA
- ORD
1 stop11h 43m
Frontier
Mon 4/207:56 pm
ORD
- SEA
1 stop23h 46m
Frontier
Deal found 3/20![Frontier logo]()
$216
This CheapOair deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/1510:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Tue 4/217:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/17![Frontier logo]()
$221
This Expedia deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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.
Wed 4/1510:57 am
SEA
- ORD
1 stop16h 53m
Multiple Airlines
Tue 4/216:00 am
ORD
- SEA
Nonstop4h 37m
Multiple Airlines
Deal found 3/17![Multiple Airlines logo]()
$229
This SmartFares 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 SmartFares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/185:49 pm
SEA
- ORD
Nonstop4h 10m
Alaska Airlines
Fri 4/248:48 pm
ORD
- SEA
Nonstop4h 41m
Alaska Airlines
Deal found 3/19![Alaska Airlines logo]()
$220
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.
Tue 4/2110:57 am
SEA
- ORD
1 stop10h 30m
Multiple Airlines
Tue 5/59:42 pm
ORD
- SEA
1 stop14h 07m
Multiple Airlines
Deal found 3/19![Multiple Airlines logo]()
$211
This Booking.com 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/2310:57 am
SEA
- ORD
1 stop17h 23m
Frontier
Mon 4/277:21 pm
ORD
- SEA
1 stop24h 21m
Frontier
Deal found 3/22![Frontier logo]()
$223
This eDestinos 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 eDestinos is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/2912:29 am
SEA
- ORD
Nonstop4h 11m
Multiple Airlines
Tue 5/59:42 pm
ORD
- SEA
1 stop14h 07m
Multiple Airlines
Deal found 3/19![Multiple Airlines logo]()
$224
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 March 22, 2026.
Search for one-way flight options from Seattle to Illinois. Find affordable one-way fares based on user searches. Data last updated March 22, 2026.
This Kiwi.com deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” 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 4/177:12 pm
SEA
- STL
1 stop22h 20m
Frontier
Deal found 3/18![Frontier logo]()
$82
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.
Wed 5/67:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 3/20![Frontier logo]()
$92
This Kiwi.com deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” 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 4/158:07 pm
SEA
- STL
1 stop21h 14m
Frontier
Deal found 3/18![Frontier logo]()
$95
This Kiwi.com deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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 4/1510:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Deal found 3/17![Frontier logo]()
$99
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 4/139:34 pm
SEA
- ORD
1 stop30h 34m
Frontier
Deal found 3/19![Frontier logo]()
$100
This Kiwi.com deal was found by Cheapflights users on 3/18. Clicking the “Pick Dates” 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 5/157:50 pm
SEA
- STL
1 stop21h 33m
Frontier
Deal found 3/18![Frontier logo]()
$100
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 4/2710:11 pm
SEA
- ORD
1 stop29h 57m
Frontier
Deal found 3/19![Frontier logo]()
$101
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.
Sat 4/187:12 pm
SEA
- ORD
1 stop12h 33m
Frontier
Deal found 3/20![Frontier logo]()
$107
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.
Fri 5/87:50 pm
SEA
- ORD
1 stop22h 47m
Frontier
Deal found 3/20![Frontier logo]()
$108
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.
Tue 4/2110:57 am
SEA
- ORD
1 stop16h 53m
Frontier
Deal found 3/20![Frontier logo]()
$110
This Expedia deal was found by Cheapflights users on 3/17. Clicking the “Pick Dates” 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.
Thu 4/2310:57 am
SEA
- ORD
1 stop17h 23m
Frontier
Deal found 3/17![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.
Tue 5/197:50 pm
SEA
- MDW
2 stops16h 22m
Frontier
Deal found 3/20![Frontier logo]()
$111
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 March 22, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $210 (Gotogate) |
One-way from | $82 (Kiwi.com) |
Popular in | December |
Cheapest in | February |
Average price | $341 |
Good round-trip deal | $297 or less |
Good one-way deal | $177 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 March 22, 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 - ORD
SEAORD
Seattle/Tacoma Intl
Thu 6/11
11:52 pm-5:58 am
Nonstop4h 06m
Chicago O'Hare Intl
Sun 6/14
9:15 pm-11:59 pm
Nonstop4h 44m
$237
Quickest round-trip
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Fri 4/17
11:55 pm-5:55 am
Nonstop4h 00m
Chicago Midway
Fri 4/24
9:35 pm-12:05 am
Nonstop4h 30m
$237
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Sat 5/2
11:55 pm-5:55 am
Nonstop4h 00m
Chicago Midway
Sat 5/9
5:30 pm-10:10 pm
1 stop6h 40m
$247
SeattleChicago
SEA - MDW
SEAMDW
Seattle/Tacoma Intl
Wed 4/15
6:00 am-12:00 pm
Nonstop4h 00m
Chicago Midway
Wed 4/22
10:15 am-12:45 pm
Nonstop4h 30m
$247
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Sat 4/18
5:49 pm-11:59 pm
Nonstop4h 10m
Chicago O'Hare Intl
Tue 4/21
8:00 am-10:43 am
Nonstop4h 43m
$255
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Fri 4/17
11:10 am-9:25 pm
1 stop8h 15m
Chicago O'Hare Intl
Thu 4/23
1:36 pm-9:50 pm
1 stop10h 14m
$257
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 4/15
10:35 am-4:39 pm
Nonstop4h 04m
Chicago O'Hare Intl
Wed 4/22
2:25 pm-11:53 pm
1 stop11h 28m
$257
SeattleSt. Louis
SEA - STL
SEASTL
Seattle/Tacoma Intl
Wed 4/29
11:45 pm-9:05 am
1 stop7h 20m
Lambert-St Louis
Wed 5/6
5:30 am-6:00 pm
2 stops14h 30m
$260
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Wed 4/15
11:35 am-11:55 pm
2 stops10h 20m
Chicago O'Hare Intl
Wed 4/22
7:45 am-1:35 pm
1 stop7h 50m
$280
SeattleChicago
SEA - ORD
SEAORD
Seattle/Tacoma Intl
Thu 4/9
5:49 pm-11:59 pm
Nonstop4h 10m
Chicago O'Hare Intl
Mon 4/13
6:00 am-8:37 am
Nonstop4h 37m
$287
Showing 1-10 of 60 resultsSorted by cheapest first
Best time to book a flight from Seattle to Illinois
Have a flexible travel schedule? Discover the best time to fly to Illinois from Seattle with our price prediction graph.
SEA-ORD
SEA-MDW
SEA-CMI
SEA-RFD
SEA-STL
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.
Cheapflights Insights
Everything you need to know about your flight from Seattle to Illinois
SEA-USIL
SEA-ORD
SEA-MDW
SEA-CMI
SEA-RFD
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 $93). Flying from Seattle to Illinois in March is currently the most expensive (average of $177). 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 March 22, 2026.
It’s typically best to fly out from Seattle to Illinois in the evening. Doing so could potentially save you 6% on the flight price compared to flying in the morning, which is usually more expensive.
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 March 14, 2026.
Travelers seeking maximum savings on their Seattle to Illinois flight should consider departing on Saturday afternoons when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
Weekly flight availability from Seattle to Illinois
Explore weekly flight availability from Seattle to Illinois. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated March 22, 2026.
The most flights from SEA to USIL are scheduled on a Friday (40 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (25 on average).
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 March 22, 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.
Food
7.0
Boarding
8.1
Overall
8.0
Comfort
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Overall
8.0
Comfort
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Overall
8.0
Comfort
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Overall
8.0
Comfort
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Overall
8.0
Comfort
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Food
7.0
Boarding
8.1
Overall
8.0
Comfort
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
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
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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 March 22, 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 March 22, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$108 | Average$286 | FlexibilityNo cancel fee | On-timeN/A | |
| Cheapest$114 | Average$258 | FlexibilityNo cancel fee | On-time85% | |
| Cheapest$162 | Average$288 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$164 | Average$399 | FlexibilityNo cancel fee | On-time69% | |
| Cheapest$169 | Average$311 | FlexibilityNo cancel fee | On-time75% | |
| Cheapest$177 | Average$337 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$177 | Average$440 | FlexibilityNo cancel fee | On-time71% |