$43+ 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 4/3. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ORD
Apr 22 — Apr 291
Round-trip
1 adult, Economy
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Find cheap flights from Denver to Illinois with Cheapflights
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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 March 23, 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 March 23, 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.
Wed 4/16:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Mon 4/68:19 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/18![Frontier logo]()
$107
This Kiwi.com deal was found by Cheapflights users on 3/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/164:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Thu 4/238:06 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/19![Frontier logo]()
$111
This Cheapflightsfares 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 Cheapflightsfares 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
Wed 5/66:51 pm
STL
- DEN
1 stop9h 34m
Frontier
Deal found 3/22![Frontier logo]()
$113
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.
Sat 4/184:20 pm
DEN
- STL
Nonstop2h 12m
Frontier
Mon 4/209:55 pm
STL
- DEN
1 stop7h 04m
Frontier
Deal found 3/20![Frontier logo]()
$114
This Booking.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 Booking.com 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 3/20![Frontier logo]()
$115
This Frontier 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 Frontier 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
Mon 5/48:17 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/19![Frontier logo]()
$120
This Super.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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/106:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Mon 4/138:19 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/18![Frontier logo]()
$121
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/44:20 pm
DEN
- STL
Nonstop2h 12m
Frontier
Wed 5/66:51 pm
STL
- DEN
1 stop9h 34m
Frontier
Deal found 3/20![Frontier logo]()
$126
This Cheapflightsfares 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 Cheapflightsfares 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
Sun 5/38:06 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/22![Frontier logo]()
$127
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/254:20 pm
DEN
- STL
Nonstop2h 12m
Frontier
Mon 4/278:17 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/22![Frontier logo]()
$128
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.
Thu 5/74:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sun 5/108:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/20![Frontier logo]()
$129
This Cheapflightsfares 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 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 3/21![Allegiant Air logo]()
$149
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 March 23, 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 March 23, 2026.
This Southwest deal was found by Cheapflights users on 3/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/52:50 pm
DEN
- ORD
1 stop8h 05m
Southwest
Thu 5/73:45 pm
ORD
- DEN
2 stops9h 00m
Southwest
Deal found 3/22![Southwest logo]()
$201
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 4/118:52 pm
DEN
- ORD
Nonstop2h 37m
United Airlines
Tue 4/148:11 pm
ORD
- DEN
Nonstop2h 59m
United Airlines
Deal found 3/18![United Airlines logo]()
$211
This Cheapflightsfares 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 3/277:00 am
DEN
- STL
1 stop15h 24m
Frontier
Sun 3/298:06 pm
STL
- DEN
1 stop29h 13m
Frontier
Deal found 3/22![Frontier logo]()
$239
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.
Wed 4/1512:35 am
DEN
- MDW
1 stop7h 12m
Delta
Mon 4/207:16 pm
MDW
- DEN
1 stop5h 03m
Delta
Deal found 3/18![Delta logo]()
$241
This American 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/56:19 am
DEN
- BMI
1 stop6h 57m
American Airlines
Tue 5/1211:16 am
BMI
- DEN
1 stop6h 46m
American Airlines
Deal found 3/18![American Airlines logo]()
$289
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.
Thu 4/2312:02 pm
DEN
- RFD
2 stops29h 17m
Multiple Airlines
Mon 4/278:35 pm
RFD
- DEN
1 stop14h 08m
Multiple Airlines
Deal found 3/20![Multiple Airlines logo]()
$356
This Southwest deal was found by Cheapflights users on 3/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/238:20 pm
DEN
- MDW
Nonstop2h 20m
Southwest
Tue 4/285:30 pm
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 3/22![Southwest logo]()
$202
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.
Thu 4/238:52 pm
DEN
- ORD
Nonstop2h 38m
United Airlines
Mon 4/2711:03 pm
ORD
- DEN
Nonstop2h 55m
United Airlines
Deal found 3/18![United Airlines logo]()
$221
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.
Thu 5/148:40 pm
DEN
- STL
Nonstop2h 10m
Southwest
Tue 5/196:35 am
STL
- DEN
Nonstop2h 20m
Southwest
Deal found 3/19![Southwest logo]()
$211
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.
Sat 5/1611:40 am
DEN
- MDW
1 stop4h 35m
Southwest
Tue 5/198:50 pm
MDW
- DEN
Nonstop2h 45m
Southwest
Deal found 3/19![Southwest logo]()
$215
This United 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/69:05 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Sun 8/95:00 am
ORD
- DEN
Nonstop2h 42m
United Airlines
Deal found 3/21![United Airlines logo]()
$245
This Southwest deal was found by Cheapflights users on 3/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/55:55 pm
DEN
- MDW
Nonstop2h 35m
Southwest
Tue 5/125:30 pm
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 3/21![Southwest logo]()
$217
This Delta deal was found by Cheapflights users on 3/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/53:30 pm
DEN
- BMI
1 stop5h 51m
Delta
Tue 5/124:14 pm
BMI
- DEN
1 stop7h 09m
Delta
Deal found 3/22![Delta logo]()
$289
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.
Thu 5/149:20 pm
DEN
- ORD
Nonstop2h 38m
United Airlines
Mon 5/189:54 pm
ORD
- DEN
Nonstop2h 56m
United Airlines
Deal found 3/22![United Airlines logo]()
$245
This Southwest deal was found by Cheapflights users on 3/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/128:40 am
DEN
- STL
1 stop3h 20m
Southwest
Thu 5/149:40 pm
STL
- DEN
Nonstop2h 20m
Southwest
Deal found 3/20![Southwest logo]()
$217
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 6/1112:55 am
DEN
- ORD
1 stop5h 31m
Delta
Fri 6/1912:15 pm
ORD
- DEN
1 stop4h 16m
Delta
Deal found 3/19![Delta logo]()
$291
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.
Thu 7/99:05 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Sun 7/125:00 am
ORD
- DEN
Nonstop2h 42m
United Airlines
Deal found 3/18![United Airlines logo]()
$245
This American 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/223:57 pm
DEN
- PIA
1 stop7h 01m
American Airlines
Mon 5/256:55 pm
PIA
- DEN
1 stop6h 04m
American Airlines
Deal found 3/18![American Airlines logo]()
$344
This Delta deal was found by Cheapflights users on 3/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/1812:59 am
DEN
- ORD
1 stop6h 06m
Delta
Mon 6/225:22 pm
ORD
- DEN
1 stop6h 31m
Delta
Deal found 3/22![Delta logo]()
$291
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 4/812:32 pm
DEN
- RFD
2 stops20h 15m
Multiple Airlines
Sun 4/1212:50 pm
RFD
- DEN
1 stop16h 09m
Multiple Airlines
Deal found 3/17![Multiple Airlines logo]()
$359
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 5/611:05 am
DEN
- MDW
1 stop4h 30m
Southwest
Sat 5/91:55 pm
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 3/21![Southwest logo]()
$223
This American 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/34:43 pm
DEN
- BMI
1 stop4h 58m
American Airlines
Sun 4/56:20 am
BMI
- DEN
1 stop8h 37m
American Airlines
Deal found 3/22![American Airlines logo]()
$364
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.
Fri 4/176:20 am
DEN
- STL
Nonstop2h 05m
Southwest
Wed 4/228:45 pm
STL
- DEN
Nonstop2h 20m
Southwest
Deal found 3/17![Southwest logo]()
$229
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.
Fri 4/105:55 pm
DEN
- PIA
Nonstop2h 24m
United Airlines
Sun 4/197:43 pm
PIA
- DEN
1 stop6h 15m
United Airlines
Deal found 3/20![United Airlines logo]()
$279
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.
Thu 4/165:45 pm
DEN
- STL
Nonstop2h 09m
United Airlines
Tue 4/218:54 am
STL
- DEN
Nonstop2h 33m
United Airlines
Deal found 3/18![United Airlines logo]()
$281
This Southwest deal was found by Cheapflights users on 3/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/182:45 pm
DEN
- STL
1 stop4h 35m
Southwest
Sat 4/256:10 am
STL
- DEN
1 stop4h 35m
Southwest
Deal found 3/20![Southwest logo]()
$234
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.
Wed 5/2712:25 pm
DEN
- MLI
1 stop8h 56m
Delta
Tue 6/25:17 pm
MLI
- DEN
1 stop6h 06m
Delta
Deal found 3/18![Delta logo]()
$344
This American 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/28:00 am
DEN
- CMI
1 stop5h 24m
American Airlines
Mon 4/62:54 pm
CMI
- DEN
1 stop6h 11m
American Airlines
Deal found 3/18![American Airlines logo]()
$388
This Southwest deal was found by Cheapflights users on 3/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 5/16:35 am
DEN
- MDW
Nonstop2h 20m
Southwest
Sun 5/36:00 am
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 3/22![Southwest logo]()
$235
This Kiwi.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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/711:00 am
DEN
- SPI
2 stops21h 26m
Multiple Airlines
Sat 4/1110:06 am
SPI
- DEN
1 stop13h 58m
Multiple Airlines
Deal found 3/22![Multiple Airlines logo]()
$459
Last-minute flights from Denver to IllinoisDiscover last-minute flight deals from Denver to Illinois. Data last updated March 23, 2026 and is based on user searches.
Discover last-minute flight deals from Denver to Illinois. Data last updated March 23, 2026 and is based on user searches.
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 4/16:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Mon 4/68:19 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/18![Frontier logo]()
$107
This Super.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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/106:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Mon 4/138:19 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/18![Frontier logo]()
$121
This Cheapflightsfares 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/1010:40 pm
DEN
- STL
1 stop12h 41m
Frontier
Sat 4/118:16 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/19![Frontier logo]()
$133
This Super.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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/119:00 pm
DEN
- ORD
Nonstop2h 38m
Frontier
Mon 4/132:29 pm
ORD
- DEN
Nonstop3h 11m
Frontier
Deal found 3/22![Frontier logo]()
$177
This Kiwi.com deal was found by Cheapflights users on 3/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/164:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Thu 4/238:06 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/19![Frontier logo]()
$111
This Cheapflightsfares 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/169:00 pm
DEN
- STL
1 stop9h 54m
Frontier
Mon 4/208:17 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/21![Frontier logo]()
$143
This Expedia 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/174:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Fri 4/248:06 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/18![Frontier logo]()
$137
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 4/179:00 pm
DEN
- ORD
1 stop16h 07m
Frontier
Tue 4/213:27 pm
ORD
- DEN
1 stop18h 58m
Frontier
Deal found 3/18![Frontier logo]()
$175
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.
Sat 4/184:20 pm
DEN
- STL
Nonstop2h 12m
Frontier
Mon 4/209:55 pm
STL
- DEN
1 stop7h 04m
Frontier
Deal found 3/20![Frontier logo]()
$114
This Expedia 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 Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/2011:59 pm
DEN
- STL
1 stop22h 20m
Frontier
Mon 4/278:17 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/19![Frontier logo]()
$134
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/254:20 pm
DEN
- STL
Nonstop2h 12m
Frontier
Mon 4/278:17 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/22![Frontier logo]()
$128
This Kiwi.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 Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 4/264:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Mon 4/278:17 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/22![Frontier logo]()
$127
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 March 23, 2026.
Search for one-way flight options from Denver to Illinois. Find affordable one-way fares based on user searches. Data last updated March 23, 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 4/36:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 3/18![Frontier logo]()
$43
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/164:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 3/18![Frontier logo]()
$44
This Cheapflightsfares 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/184:20 pm
DEN
- STL
Nonstop2h 12m
Frontier
Deal found 3/20![Frontier logo]()
$54
This Kiwi.com deal was found by Cheapflights users on 3/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/164:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Deal found 3/19![Frontier logo]()
$55
This Frontier 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 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
Deal found 3/20![Frontier logo]()
$56
This Super.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 Super.com 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
Deal found 3/18![Frontier logo]()
$63
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 4/234:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Deal found 3/21![Frontier logo]()
$64
This Frontier 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 Frontier 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 3/18![Frontier logo]()
$66
This Super.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 Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/1911:54 pm
DEN
- STL
1 stop8h 01m
Frontier
Deal found 3/20![Frontier logo]()
$69
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 5/1711:54 pm
DEN
- STL
1 stop8h 01m
Frontier
Deal found 3/20![Frontier logo]()
$70
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 5/1811:54 pm
DEN
- ORD
1 stop7h 01m
Frontier
Deal found 3/20![Frontier logo]()
$90
This CheapOair deal was found by Cheapflights users on 3/20. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/281:09 pm
DEN
- MDW
1 stop8h 05m
Frontier
Deal found 3/20![Frontier logo]()
$90
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 March 23, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $107 (Kiwi.com) |
One-way from | $43 (Kiwi.com) |
Popular in | March |
Cheapest in | August |
Average price | $275 |
Good round-trip deal | $259 or less |
Good one-way deal | $149 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 March 23, 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 - ORD
DENORD
Denver Intl
Tue 5/5
2:50 pm-11:55 pm
1 stop8h 05m
Chicago O'Hare Intl
Thu 5/7
3:45 pm-11:45 pm
2 stops9h 00m
$201
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Thu 4/23
8:20 pm-11:40 pm
Nonstop2h 20m
Chicago Midway
Tue 4/28
5:30 pm-7:10 pm
Nonstop2h 40m
$202
DenverChicago
DEN - ORD
DENORD
Denver Intl
Sat 4/11
8:52 pm-12:29 am
Nonstop2h 37m
Chicago O'Hare Intl
Tue 4/14
8:11 pm-10:10 pm
Nonstop2h 59m
$211
DenverSt. Louis
DEN - STL
DENSTL
Denver Intl
Thu 5/14
8:40 pm-11:50 pm
Nonstop2h 10m
Lambert-St Louis
Tue 5/19
6:35 am-7:55 am
Nonstop2h 20m
$211
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Sat 5/16
11:40 am-5:15 pm
1 stop4h 35m
Chicago Midway
Tue 5/19
8:50 pm-10:35 pm
Nonstop2h 45m
$215
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Tue 5/5
5:55 pm-9:30 pm
Nonstop2h 35m
Chicago Midway
Tue 5/12
5:30 pm-7:10 pm
Nonstop2h 40m
$217
DenverSt. Louis
DEN - STL
DENSTL
Denver Intl
Tue 5/12
8:40 am-1:00 pm
1 stop3h 20m
Lambert-St Louis
Thu 5/14
9:40 pm-11:00 pm
Nonstop2h 20m
$217
DenverChicago
DEN - ORD
DENORD
Denver Intl
Thu 4/23
8:52 pm-12:30 am
Nonstop2h 38m
Chicago O'Hare Intl
Mon 4/27
11:03 pm-12:58 am
Nonstop2h 55m
$221
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Wed 5/6
11:05 am-4:35 pm
1 stop4h 30m
Chicago Midway
Sat 5/9
1:55 pm-3:35 pm
Nonstop2h 40m
$223
Quickest round-trip
DenverSt. Louis
DEN - STL
DENSTL
Denver Intl
Fri 4/17
6:20 am-9:25 am
Nonstop2h 05m
Lambert-St Louis
Wed 4/22
8:45 pm-10:05 pm
Nonstop2h 20m
$229
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-ORD
DEN-MDW
DEN-BMI
DEN-RFD
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-ORD
DEN-MDW
DEN-BMI
What is the cheapest month to book a flight from Denver to Illinois?
Currently, July is the cheapest month in which you can book a flight from Denver to Illinois (average of $46). Flying from Denver to Illinois in June is currently the most expensive (average of $140). 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 March 23, 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 at noon.
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 March 23, 2026.
The most flights from DEN to USIL are scheduled on a Friday (56 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (38 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 23, 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.
Overall
8.0
Entertainment
7.5
Food
7.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Overall
8.0
Entertainment
7.5
Food
7.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Overall
8.0
Entertainment
7.5
Food
7.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Overall
8.0
Entertainment
7.5
Food
7.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Overall
8.0
Entertainment
7.5
Food
7.0
Boarding
8.1
Comfort
8.0
Crew
8.6
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Overall
8.0
Entertainment
7.5
Food
7.0
Boarding
8.1
Comfort
8.0
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 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 March 23, 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 March 23, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$57 | Average$140 | FlexibilityNo cancel fee | On-time88% | |
| Cheapest$74 | Average$185 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$126 | Average$191 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$155 | Average$267 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$157 | Average$402 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$161 | Average$352 | FlexibilityNo cancel fee | On-time69% |