$53+ Cheap flights from Denver (DEN) 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 5/17. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ORD
May 21 — May 281
Round-trip
1 adult, Economy
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Cheapest flights from Denver to IllinoisExplore the most affordable flight options available from Denver to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 21, 2026.
Explore the most affordable flight options available from Denver to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on April 21, 2026.
This Cheapflightsfares deal was found by Cheapflights users on 4/20. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/272:17 pm
DEN
- PIA
Nonstop2h 07m
Allegiant Air
Sun 8/3010:07 am
PIA
- DEN
Nonstop2h 19m
Allegiant Air
Deal found 4/20![Allegiant Air logo]()
$106
This Cheapflightsfares deal was found by Cheapflights users on 4/19. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/94:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 5/119:18 pm
STL
- DEN
1 stop7h 07m
Frontier
Deal found 4/19![Frontier logo]()
$113
This Frontier deal was found by Cheapflights users on 4/18. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/184:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Fri 5/229:06 pm
STL
- DEN
1 stop7h 19m
Frontier
Deal found 4/18![Frontier logo]()
$116
This Frontier deal was found by Cheapflights users on 4/18. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/174:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Wed 5/278:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/18![Frontier logo]()
$118
This deal was found by Cheapflights users on 4/18. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/14:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Sat 5/98:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/18![Frontier logo]()
$119
This Cheapflightsfares deal was found by Cheapflights users on 4/17. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/511:54 pm
DEN
- STL
1 stop8h 01m
Frontier
Sat 5/98:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/17![Frontier logo]()
$124
This Cheapflightsfares deal was found by Cheapflights users on 4/18. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/294:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 6/18:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/18![Frontier logo]()
$126
This Kiwi.com deal was found by Cheapflights users on 4/16. 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.
Thu 5/144:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 5/185:27 pm
STL
- DEN
1 stop21h 37m
Frontier
Deal found 4/16![Frontier logo]()
$127
This Frontier deal was found by Cheapflights users on 4/18. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/174:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Fri 5/228:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/18![Frontier logo]()
$128
This Cheapflightsfares deal was found by Cheapflights users on 4/17. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/214:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 5/259:06 pm
STL
- DEN
1 stop28h 03m
Frontier
Deal found 4/17![Frontier logo]()
$129
This Cheapflightsfares deal was found by Cheapflights users on 4/21. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/154:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sun 5/1712:36 pm
STL
- DEN
1 stop12h 33m
Frontier
Deal found 4/21![Frontier logo]()
$130
This Cheapflightsfares deal was found by Cheapflights users on 4/21. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/102:16 pm
DEN
- PIA
Nonstop2h 03m
Allegiant Air
Sun 9/1310:07 am
PIA
- DEN
Nonstop2h 20m
Allegiant Air
Deal found 4/21![Allegiant Air logo]()
$157
Best flights from Denver to IllinoisDiscover carefully curated flight deals from Denver to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated April 21, 2026.
Discover carefully curated flight deals from Denver to Illinois that have cost, travel time, and layovers in mind to ensure you get the best travel experience. Data last updated April 21, 2026.
This Southwest deal was found by Cheapflights users on 4/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/283:00 pm
DEN
- MDW
1 stop4h 25m
Southwest
Mon 6/16:00 am
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 4/20![Southwest logo]()
$220
This United Airlines deal was found by Cheapflights users on 4/17. 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 6/49:05 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Mon 6/810:55 pm
ORD
- DEN
Nonstop2h 58m
United Airlines
Deal found 4/17![United Airlines logo]()
$221
This Delta deal was found by Cheapflights users on 4/21. 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.
Wed 8/1210:45 am
DEN
- ORD
1 stop8h 32m
Delta
Fri 8/143:50 pm
ORD
- DEN
1 stop7h 39m
Delta
Deal found 4/21![Delta logo]()
$229
This Kiwi.com deal was found by Cheapflights users on 4/17. 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.
Fri 5/86:45 am
DEN
- RFD
1 stop12h 00m
Multiple Airlines
Mon 5/117:09 pm
RFD
- DEN
1 stop21h 53m
Multiple Airlines
Deal found 4/17![Multiple Airlines logo]()
$313
This American Airlines deal was found by Cheapflights users on 4/20. 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.
Wed 5/67:36 am
DEN
- CMI
1 stop5h 32m
American Airlines
Sun 5/106:55 pm
CMI
- DEN
1 stop6h 11m
American Airlines
Deal found 4/20![American Airlines logo]()
$328
This Southwest deal was found by Cheapflights users on 4/17. 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.
Thu 6/118:50 pm
DEN
- MDW
Nonstop2h 20m
Southwest
Tue 6/169:05 pm
MDW
- DEN
Nonstop2h 45m
Southwest
Deal found 4/17![Southwest logo]()
$233
This Delta deal was found by Cheapflights users on 4/18. 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.
Tue 8/2512:55 am
DEN
- MDW
1 stop6h 47m
Delta
Fri 8/285:25 pm
MDW
- DEN
1 stop7h 20m
Delta
Deal found 4/18![Delta logo]()
$253
This United Airlines deal was found by Cheapflights users on 4/16. 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/316:00 am
DEN
- ORD
Nonstop2h 42m
United Airlines
Fri 6/56:00 am
ORD
- DEN
Nonstop2h 42m
United Airlines
Deal found 4/16![United Airlines logo]()
$265
This Southwest deal was found by Cheapflights users on 4/21. 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 5/136:35 am
DEN
- MDW
Nonstop2h 20m
Southwest
Mon 5/189:35 pm
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 4/21![Southwest logo]()
$242
This United Airlines deal was found by Cheapflights users on 4/20. 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.
Fri 8/77:40 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Sun 8/911:00 pm
ORD
- DEN
Nonstop2h 58m
United Airlines
Deal found 4/20![United Airlines logo]()
$265
This Southwest deal was found by Cheapflights users on 4/19. 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.
Sat 5/166:30 am
DEN
- MDW
Nonstop2h 20m
Southwest
Tue 5/1910:10 am
MDW
- DEN
1 stop4h 55m
Southwest
Deal found 4/19![Southwest logo]()
$247
This Delta deal was found by Cheapflights users on 4/18. 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.
Wed 6/312:55 am
DEN
- MDW
1 stop6h 48m
Delta
Tue 6/99:54 am
MDW
- DEN
1 stop6h 46m
Delta
Deal found 4/18![Delta logo]()
$275
This United Airlines deal was found by Cheapflights users on 4/20. 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 7/307:40 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Thu 8/65:00 am
ORD
- DEN
Nonstop2h 42m
United Airlines
Deal found 4/20![United Airlines logo]()
$265
This Kiwi.com deal was found by Cheapflights users on 4/21. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/209:03 am
DEN
- RFD
1 stop10h 02m
Multiple Airlines
Mon 5/259:13 pm
RFD
- DEN
1 stop25h 36m
Multiple Airlines
Deal found 4/21![Multiple Airlines logo]()
$329
This Delta deal was found by Cheapflights users on 4/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/256:05 am
DEN
- ORD
1 stop5h 56m
Delta
Fri 5/298:05 pm
ORD
- DEN
1 stop4h 36m
Delta
Deal found 4/19![Delta logo]()
$285
This Southwest deal was found by Cheapflights users on 4/21. 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.
Fri 8/1411:00 am
DEN
- MDW
1 stop5h 05m
Southwest
Sun 8/167:55 am
MDW
- DEN
Nonstop2h 45m
Southwest
Deal found 4/21![Southwest logo]()
$263
This United Airlines deal was found by Cheapflights users on 4/19. 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.
Sat 7/114:20 pm
DEN
- CMI
1 stop5h 20m
United Airlines
Sat 7/257:34 pm
CMI
- DEN
1 stop5h 15m
United Airlines
Deal found 4/19![United Airlines logo]()
$274
This Kiwi.com deal was found by Cheapflights users on 4/17. 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.
Fri 5/86:45 am
DEN
- RFD
1 stop12h 00m
Multiple Airlines
Wed 5/1312:09 pm
RFD
- DEN
1 stop11h 30m
Multiple Airlines
Deal found 4/17![Multiple Airlines logo]()
$332
This Delta deal was found by Cheapflights users on 4/17. 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.
Fri 10/1612:55 am
DEN
- ORD
1 stop6h 05m
Delta
Mon 10/195:20 pm
ORD
- DEN
1 stop6h 39m
Delta
Deal found 4/17![Delta logo]()
$285
This Southwest deal was found by Cheapflights users on 4/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/286:05 am
DEN
- ORD
1 stop6h 10m
Southwest
Fri 5/292:40 pm
ORD
- DEN
2 stops10h 05m
Southwest
Deal found 4/20![Southwest logo]()
$267
This Kiwi.com deal was found by Cheapflights users on 4/19. 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.
Wed 7/159:01 am
DEN
- RFD
1 stop9h 58m
Multiple Airlines
Wed 7/228:49 pm
RFD
- DEN
1 stop12h 22m
Multiple Airlines
Deal found 4/19![Multiple Airlines logo]()
$335
This United Airlines deal was found by Cheapflights users on 4/17. 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 6/96:00 am
DEN
- MLI
1 stop5h 39m
United Airlines
Sun 6/289:05 am
MLI
- DEN
Nonstop2h 30m
United Airlines
Deal found 4/17![United Airlines logo]()
$279
This American Airlines deal was found by Cheapflights users on 4/17. 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.
Tue 6/236:22 am
DEN
- CMI
1 stop6h 53m
American Airlines
Fri 6/2611:40 am
CMI
- DEN
1 stop6h 14m
American Airlines
Deal found 4/17![American Airlines logo]()
$416
This Delta deal was found by Cheapflights users on 4/19. 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.
Sat 5/236:05 am
DEN
- MDW
1 stop5h 37m
Delta
Sat 5/235:10 pm
MDW
- DEN
1 stop8h 23m
Delta
Deal found 4/19![Delta logo]()
$285
This Southwest deal was found by Cheapflights users on 4/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/281:00 pm
DEN
- ORD
2 stops9h 55m
Southwest
Mon 6/13:45 pm
ORD
- DEN
1 stop6h 05m
Southwest
Deal found 4/20![Southwest logo]()
$268
This American Airlines deal was found by Cheapflights users on 4/19. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/296:55 am
DEN
- SPI
1 stop6h 06m
American Airlines
Tue 6/26:00 am
SPI
- DEN
1 stop6h 33m
American Airlines
Deal found 4/19![American Airlines logo]()
$417
This Delta deal was found by Cheapflights users on 4/20. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/133:15 pm
DEN
- MLI
1 stop6h 06m
Delta
Mon 5/185:17 pm
MLI
- DEN
1 stop8h 16m
Delta
Deal found 4/20![Delta logo]()
$289
This Kiwi.com deal was found by Cheapflights users on 4/16. 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.
Thu 5/77:01 pm
DEN
- BMI
2 stops24h 14m
Multiple Airlines
Thu 5/149:33 am
BMI
- DEN
1 stop14h 38m
Multiple Airlines
Deal found 4/16![Multiple Airlines logo]()
$354
This United Airlines deal was found by Cheapflights users on 4/19. 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.
Sat 5/235:38 pm
DEN
- MLI
Nonstop2h 16m
United Airlines
Wed 5/275:39 pm
MLI
- DEN
1 stop5h 25m
United Airlines
Deal found 4/19![United Airlines logo]()
$299
This Southwest deal was found by Cheapflights users on 4/17. 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.
Tue 5/1211:00 am
DEN
- MDW
2 stops5h 10m
Southwest
Tue 5/195:30 am
MDW
- DEN
1 stop5h 40m
Southwest
Deal found 4/17![Southwest logo]()
$278
Last-minute flights from Denver to IllinoisDiscover last-minute flight deals from Denver to Illinois. Data last updated April 21, 2026 and is based on user searches.
Discover last-minute flight deals from Denver to Illinois. Data last updated April 21, 2026 and is based on user searches.
This Frontier deal was found by Cheapflights users on 4/19. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/2810:29 pm
DEN
- ORD
1 stop6h 39m
Frontier
Tue 5/59:37 pm
ORD
- DEN
Nonstop3h 07m
Frontier
Deal found 4/19![Frontier logo]()
$185
This deal was found by Cheapflights users on 4/18. 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 is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/14:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Sat 5/98:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/18![Frontier logo]()
$119
This Cheapflightsfares deal was found by Cheapflights users on 4/17. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/511:54 pm
DEN
- STL
1 stop8h 01m
Frontier
Sat 5/98:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/17![Frontier logo]()
$124
This Cheapflightsfares deal was found by Cheapflights users on 4/19. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/94:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 5/119:18 pm
STL
- DEN
1 stop7h 07m
Frontier
Deal found 4/19![Frontier logo]()
$113
This Kiwi.com deal was found by Cheapflights users on 4/16. 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.
Thu 5/144:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 5/185:27 pm
STL
- DEN
1 stop21h 37m
Frontier
Deal found 4/16![Frontier logo]()
$127
This Cheapflightsfares deal was found by Cheapflights users on 4/21. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/154:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sun 5/1712:36 pm
STL
- DEN
1 stop12h 33m
Frontier
Deal found 4/21![Frontier logo]()
$130
This Frontier deal was found by Cheapflights users on 4/18. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/174:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sat 5/238:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/18![Frontier logo]()
$118
This Frontier deal was found by Cheapflights users on 4/18. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/174:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Fri 5/228:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/18![Frontier logo]()
$128
This Frontier deal was found by Cheapflights users on 4/18. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/184:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Fri 5/229:06 pm
STL
- DEN
1 stop7h 19m
Frontier
Deal found 4/18![Frontier logo]()
$116
This Cheapflightsfares deal was found by Cheapflights users on 4/17. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/214:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 5/259:06 pm
STL
- DEN
1 stop28h 03m
Frontier
Deal found 4/17![Frontier logo]()
$129
This Cheapflightsfares deal was found by Cheapflights users on 4/18. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/244:27 pm
DEN
- PIA
Nonstop2h 03m
Allegiant Air
Sun 5/3111:09 am
PIA
- DEN
Nonstop2h 23m
Allegiant Air
Deal found 4/18![Allegiant Air logo]()
$172
This Cheapflightsfares deal was found by Cheapflights users on 4/18. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/294:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 6/18:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/18![Frontier logo]()
$126
One-way flights from Denver to IllinoisSearch for one-way flight options from Denver to Illinois. Find affordable one-way fares based on user searches. Data last updated April 21, 2026.
Search for one-way flight options from Denver to Illinois. Find affordable one-way fares based on user searches. Data last updated April 21, 2026.
This Kiwi.com deal was found by Cheapflights users on 4/17. 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.
Sun 5/174:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/17![Frontier logo]()
$53
This Kiwi.com deal was found by Cheapflights users on 4/21. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 6/84:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/21![Frontier logo]()
$59
This Super.com deal was found by Cheapflights users on 4/18. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 5/144:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/18![Frontier logo]()
$61
This Super.com deal was found by Cheapflights users on 4/21. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/24:20 pm
DEN
- STL
Nonstop2h 12m
Frontier
Deal found 4/21![Frontier logo]()
$63
This Frontier deal was found by Cheapflights users on 4/20. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/94:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 4/20![Frontier logo]()
$64
This Super.com deal was found by Cheapflights users on 4/16. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/1211:54 pm
DEN
- STL
1 stop8h 01m
Frontier
Deal found 4/16![Frontier logo]()
$69
This Cheapflightsfares deal was found by Cheapflights users on 4/20. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/2411:54 pm
DEN
- STL
1 stop8h 01m
Frontier
Deal found 4/20![Frontier logo]()
$70
This Cheapflightsfares deal was found by Cheapflights users on 4/20. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/272:17 pm
DEN
- PIA
Nonstop2h 07m
Allegiant Air
Deal found 4/20![Allegiant Air logo]()
$73
This Super.com deal was found by Cheapflights users on 4/16. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 6/54:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/16![Frontier logo]()
$73
This Kiwi.com deal was found by Cheapflights users on 4/21. 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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/235:05 pm
DEN
- ORD
Nonstop2h 38m
Frontier
Deal found 4/21![Frontier logo]()
$87
This Super.com deal was found by Cheapflights users on 4/16. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/46:45 am
DEN
- ORD
1 stop8h 17m
Frontier
Deal found 4/16![Frontier logo]()
$89
This Super.com deal was found by Cheapflights users on 4/19. 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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/65:05 am
DEN
- MDW
1 stop8h 07m
Frontier
Deal found 4/19![Frontier logo]()
$89
Find flight deals from Denver to Illinois
Keep the following information in mind while searching for Denver to Illinois flight deals. Data was last updated April 21, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $106 (Cheapflightsfares) |
One-way from | $53 (Kiwi.com) |
Popular in | March |
Cheapest in | August |
Average price | $279 |
Good round-trip deal | $271 or less |
Good one-way deal | $74 or less |
Cheapflights Fare Finder
Customize your flight search to find flights from Denver 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 April 21, 2026.
Use the filters below to find and compare flights from Denver to Illinois that are best for you.
Fly from
Fly to
Route
Depart
Return
Cheapest round-trip
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Thu 5/28
3:00 pm-8:25 pm
1 stop4h 25m
Chicago Midway
Mon 6/1
6:00 am-7:40 am
Nonstop2h 40m
$220
DenverChicago
DEN - ORD
DENORD
Denver Intl
Thu 6/4
9:05 pm-12:44 am
Nonstop2h 39m
Chicago O'Hare Intl
Mon 6/8
10:55 pm-12:53 am
Nonstop2h 58m
$221
DenverChicago
DEN - ORD
DENORD
Denver Intl
Wed 8/12
10:45 am-8:17 pm
1 stop8h 32m
Chicago O'Hare Intl
Fri 8/14
3:50 pm-10:29 pm
1 stop7h 39m
$229
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Thu 6/11
8:50 pm-12:10 am
Nonstop2h 20m
Chicago Midway
Tue 6/16
9:05 pm-10:50 pm
Nonstop2h 45m
$233
Quickest round-trip
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Wed 5/13
6:35 am-9:55 am
Nonstop2h 20m
Chicago Midway
Mon 5/18
9:35 pm-11:15 pm
Nonstop2h 40m
$242
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Sat 5/16
6:30 am-9:50 am
Nonstop2h 20m
Chicago Midway
Tue 5/19
10:10 am-2:05 pm
1 stop4h 55m
$247
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Tue 8/25
12:55 am-8:42 am
1 stop6h 47m
Chicago Midway
Fri 8/28
5:25 pm-11:45 pm
1 stop7h 20m
$253
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Fri 8/14
11:00 am-5:05 pm
1 stop5h 05m
Chicago Midway
Sun 8/16
7:55 am-9:40 am
Nonstop2h 45m
$263
DenverChicago
DEN - ORD
DENORD
Denver Intl
Sun 5/31
6:00 am-9:42 am
Nonstop2h 42m
Chicago O'Hare Intl
Fri 6/5
6:00 am-7:42 am
Nonstop2h 42m
$265
DenverChicago
DEN - ORD
DENORD
Denver Intl
Fri 8/7
7:40 pm-11:19 pm
Nonstop2h 39m
Chicago O'Hare Intl
Sun 8/9
11:00 pm-12:58 am
Nonstop2h 58m
$265
Showing 1-10 of 60 resultsSorted by cheapest first
Best time to book a flight from Denver to Illinois
Have a flexible travel schedule? Discover the best time to fly to Illinois from Denver with our price prediction graph.
DEN-STL
DEN-PIA
DEN-ORD
DEN-MDW
DEN-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 Denver to Illinois
DEN-USIL
DEN-STL
DEN-PIA
DEN-ORD
DEN-MDW
What is the cheapest month to book a flight from Denver to Illinois?
Currently, August is the cheapest month in which you can book a flight from Denver to Illinois (average of $218). Flying from Denver to Illinois in December is currently the most expensive (average of $460). 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 DEN to IL?
Find hourly flight availability from Denver 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 April 21, 2026.
It’s optimal to fly from Denver to Illinois in the morning. By choosing this option you can save up to 22% on the cost of your flight, compared to a flight in the afternoon.
What is the cheapest day to fly from Denver to Illinois?
Use this chart to determine the cheapest time to fly round-trip from Denver to Illinois. Price data was last updated on May 11, 2025.
Travelers seeking maximum savings on their Denver to Illinois flight should consider departing on Friday at noon when fares are most often at their lowest. Wednesday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
Weekly flight availability from Denver to Illinois
Explore weekly flight availability from Denver 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 April 21, 2026.
The most flights from DEN to USIL are scheduled on a Monday (62 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (45 on average).
How much does it cost to fly round-trip from Denver to Illinois?
Reviews of airlines servicing Illinois
Get insights into the airlines that provide service to Illinois. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Illinois. Reviews last updated April 21, 2026.
Read through reviews of airlines operating flights from Denver to Illinois, such as Southwest,United Airlines, andAllegiant Air. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Boarding
8.1
Entertainment
7.5
Comfort
8.0
Overall
8.0
Crew
8.6
Food
7.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Related info for your journey
Find useful and relevant information for your journey from Denver 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 Denver 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 Denver to Illinois by cabin class
Find flights from Denver to Illinois, based on your preferred cabin class, be it economy, premium economy, business, or first class.
Denver and Illinois flights
Browse other Denver and Illinois flight options. Last updated on April 21, 2026.
Popular flight searches
Check out other popular destinations found by fellow travelers in 2026
Denver to Illinois flights
Consider these flights traveling from Denver to Illinois.
Top 6 airlines flying from Denver to Illinois
Discover the top 6 airlines that operate flights from Denver 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 April 21, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$54 | Average$145 | FlexibilityNo cancel fee | On-time88% | |
| Cheapest$74 | Average$188 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$126 | Average$191 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$157 | Average$270 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$159 | Average$398 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$167 | Average$364 | FlexibilityNo cancel fee | On-time69% |