$49+ 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 5/11. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ORD
May 27 — Jun 31
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 27, 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 27, 2026.
This Cheapflightsfares deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 6/19:21 pm
STL
- DEN
1 stop21h 43m
Frontier
Deal found 4/27![Frontier logo]()
$117
This Cheapflightsfares deal was found by Cheapflights users on 4/22. 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 5/164:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sat 5/238:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/22![Frontier logo]()
$119
This Frontier deal was found by Cheapflights users on 4/22. 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.
Thu 5/284:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sat 6/68:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/22![Frontier logo]()
$120
This Kiwi.com deal was found by Cheapflights users on 4/22. 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.
Thu 5/284:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sat 5/308:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/22![Frontier logo]()
$122
This Cheapflightsfares deal was found by Cheapflights users on 4/22. 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.
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Wed 6/36:51 pm
STL
- DEN
1 stop9h 34m
Frontier
Deal found 4/22![Frontier logo]()
$123
This Frontier deal was found by Cheapflights users on 4/22. 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.
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Fri 5/299:06 pm
STL
- DEN
1 stop7h 19m
Frontier
Deal found 4/22![Frontier logo]()
$124
This Cheapflightsfares deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” 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
Sat 5/168:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/26![Frontier logo]()
$127
This Frontier deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” 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 5/264:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Tue 6/28:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/23![Frontier logo]()
$128
This Frontier deal was found by Cheapflights users on 4/22. 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.
Sun 5/246:30 am
DEN
- STL
1 stop10h 03m
Frontier
Sat 6/68:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/22![Frontier logo]()
$130
This Kiwi.com deal was found by Cheapflights users on 4/22. 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.
Wed 6/34:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Tue 6/97:19 pm
STL
- DEN
1 stop12h 12m
Frontier
Deal found 4/22![Frontier logo]()
$131
This Cheapflightsfares deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” 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 4/26![Allegiant Air logo]()
$149
This Cheapflightsfares deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/111:46 pm
DEN
- ORD
1 stop7h 17m
Frontier
Mon 7/69:57 pm
ORD
- DEN
Nonstop3h 00m
Frontier
Deal found 4/27![Frontier logo]()
$187
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 27, 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 27, 2026.
This Southwest deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/206:35 am
DEN
- MDW
Nonstop2h 20m
Southwest
Tue 5/268:50 pm
MDW
- DEN
Nonstop2h 45m
Southwest
Deal found 4/27![Southwest logo]()
$201
This United Airlines deal was found by Cheapflights users on 4/22. 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.
Wed 5/205:34 pm
DEN
- STL
Nonstop2h 09m
United Airlines
Wed 5/274:48 pm
STL
- DEN
Nonstop2h 35m
United Airlines
Deal found 4/22![United Airlines logo]()
$219
This Delta deal was found by Cheapflights users on 4/25. Clicking the “Pick Dates” 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 6/105:45 am
DEN
- ORD
1 stop5h 51m
Delta
Wed 6/175:57 pm
ORD
- DEN
1 stop6h 34m
Delta
Deal found 4/25![Delta logo]()
$221
This Kiwi.com deal was found by Cheapflights users on 4/22. 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.
Thu 5/284:27 pm
DEN
- PIA
Nonstop2h 03m
Multiple Airlines
Sun 5/319:06 pm
PIA
- DEN
1 stop12h 02m
Multiple Airlines
Deal found 4/22![Multiple Airlines logo]()
$243
This American Airlines deal was found by Cheapflights users on 4/25. Clicking the “Pick Dates” 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 5/296:22 am
DEN
- CMI
1 stop6h 53m
American Airlines
Tue 6/26:39 pm
CMI
- DEN
1 stop6h 20m
American Airlines
Deal found 4/25![American Airlines logo]()
$294
This Southwest deal was found by Cheapflights users on 4/22. 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.
Wed 5/205:55 am
DEN
- STL
Nonstop2h 05m
Southwest
Wed 5/278:45 pm
STL
- DEN
Nonstop2h 20m
Southwest
Deal found 4/22![Southwest logo]()
$219
This Delta deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” 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 6/16:05 am
DEN
- MDW
1 stop5h 37m
Delta
Sat 6/61:59 pm
MDW
- DEN
1 stop7h 16m
Delta
Deal found 4/23![Delta logo]()
$225
This United Airlines deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/2010:05 am
DEN
- STL
Nonstop2h 08m
United Airlines
Wed 5/205:59 pm
STL
- DEN
Nonstop2h 33m
United Airlines
Deal found 4/26![United Airlines logo]()
$227
This Delta deal was found by Cheapflights users on 4/24. Clicking the “Pick Dates” 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 6/69:49 am
DEN
- MDW
1 stop5h 46m
Delta
Tue 6/166:05 am
MDW
- DEN
1 stop6h 02m
Delta
Deal found 4/24![Delta logo]()
$231
This Southwest deal was found by Cheapflights users on 4/24. Clicking the “Pick Dates” 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 6/2410:15 am
DEN
- MDW
1 stop5h 35m
Southwest
Tue 6/305:30 am
MDW
- DEN
Nonstop2h 35m
Southwest
Deal found 4/24![Southwest logo]()
$233
This Southwest deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/235:45 pm
DEN
- MDW
Nonstop2h 35m
Southwest
Wed 6/312:20 pm
MDW
- DEN
1 stop6h 00m
Southwest
Deal found 4/27![Southwest logo]()
$243
This Kiwi.com deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” 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 6/19:13 pm
RFD
- DEN
2 stops37h 51m
Multiple Airlines
Deal found 4/23![Multiple Airlines logo]()
$295
This United Airlines deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” 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 8/84:40 pm
DEN
- CMI
1 stop5h 00m
United Airlines
Sat 8/151:32 pm
CMI
- DEN
1 stop7h 07m
United Airlines
Deal found 4/26![United Airlines logo]()
$270
This Delta deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” 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 8/126:10 am
DEN
- MDW
1 stop6h 01m
Delta
Fri 8/146:45 pm
MDW
- DEN
1 stop4h 44m
Delta
Deal found 4/26![Delta logo]()
$253
This American Airlines deal was found by Cheapflights users on 4/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/233:11 pm
DEN
- CMI
1 stop5h 50m
American Airlines
Sun 5/246:39 pm
CMI
- DEN
1 stop6h 20m
American Airlines
Deal found 4/24![American Airlines logo]()
$318
This United Airlines deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” 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 5/229:05 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Sat 5/307:05 am
ORD
- DEN
Nonstop2h 50m
United Airlines
Deal found 4/26![United Airlines logo]()
$273
This Southwest deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” 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 5/235:45 pm
DEN
- MDW
Nonstop2h 35m
Southwest
Sun 5/248:30 am
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 4/26![Southwest logo]()
$251
This American Airlines deal was found by Cheapflights users on 4/25. Clicking the “Pick Dates” 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 5/1010:37 am
DEN
- CMI
1 stop6h 47m
American Airlines
Sun 5/316:39 pm
CMI
- DEN
1 stop6h 20m
American Airlines
Deal found 4/25![American Airlines logo]()
$323
This Delta deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/2012:55 am
DEN
- ORD
1 stop6h 50m
Delta
Sun 5/248:42 am
ORD
- DEN
1 stop4h 30m
Delta
Deal found 4/27![Delta logo]()
$271
This Kiwi.com deal was found by Cheapflights users on 4/22. 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.
Wed 6/39:03 am
DEN
- RFD
1 stop9h 57m
Multiple Airlines
Sun 6/711:27 am
RFD
- DEN
2 stops22h 38m
Multiple Airlines
Deal found 4/22![Multiple Airlines logo]()
$338
This Southwest deal was found by Cheapflights users on 4/22. 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.
Sat 6/275:15 am
DEN
- MDW
Nonstop2h 20m
Southwest
Wed 7/15:30 am
MDW
- DEN
Nonstop2h 35m
Southwest
Deal found 4/22![Southwest logo]()
$255
This United Airlines deal was found by Cheapflights users on 4/22. 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
Wed 5/279:54 pm
ORD
- DEN
Nonstop2h 59m
United Airlines
Deal found 4/22![United Airlines logo]()
$294
This American Airlines deal was found by Cheapflights users on 4/24. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/95:30 am
DEN
- CMI
1 stop8h 01m
American Airlines
Wed 5/136:55 pm
CMI
- DEN
1 stop6h 11m
American Airlines
Deal found 4/24![American Airlines logo]()
$328
This Delta deal was found by Cheapflights users on 4/22. 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 5/1412:55 am
DEN
- MDW
1 stop6h 48m
Delta
Sun 5/244:30 pm
MDW
- DEN
1 stop9h 03m
Delta
Deal found 4/22![Delta logo]()
$273
This Southwest deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” 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 7/238:50 pm
DEN
- MDW
Nonstop2h 20m
Southwest
Thu 7/306:45 am
MDW
- DEN
Nonstop2h 35m
Southwest
Deal found 4/26![Southwest logo]()
$265
This Kiwi.com deal was found by Cheapflights users on 4/25. Clicking the “Pick Dates” 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 6/59:03 am
DEN
- RFD
1 stop10h 17m
Multiple Airlines
Mon 6/89:10 pm
RFD
- DEN
1 stop23h 36m
Multiple Airlines
Deal found 4/25![Multiple Airlines logo]()
$356
This United Airlines deal was found by Cheapflights users on 4/22. 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 6/165:33 pm
DEN
- PIA
Nonstop2h 28m
United Airlines
Tue 6/235:33 pm
PIA
- DEN
1 stop7h 04m
United Airlines
Deal found 4/22![United Airlines logo]()
$299
This Delta deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” 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 10/106:45 am
DEN
- ORD
1 stop4h 52m
Delta
Sat 10/1711:30 am
ORD
- DEN
1 stop7h 00m
Delta
Deal found 4/23![Delta logo]()
$285
This Southwest deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 9/311:00 am
DEN
- MDW
1 stop5h 00m
Southwest
Sun 9/69:15 am
MDW
- DEN
1 stop4h 40m
Southwest
Deal found 4/23![Southwest logo]()
$269
This United Airlines deal was found by Cheapflights users on 4/24. Clicking the “Pick Dates” 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
Tue 5/265:39 pm
MLI
- DEN
1 stop7h 14m
United Airlines
Deal found 4/24![United Airlines logo]()
$299
Last-minute flights from Denver to IllinoisDiscover last-minute flight deals from Denver to Illinois. Data last updated April 27, 2026 and is based on user searches.
Discover last-minute flight deals from Denver to Illinois. Data last updated April 27, 2026 and is based on user searches.
This Cheapflightsfares deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” 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
Sat 5/168:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/26![Frontier logo]()
$127
This Super.com deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” 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.
Sun 5/104:54 pm
DEN
- ORD
Nonstop2h 38m
Frontier
Sat 5/169:37 pm
ORD
- DEN
Nonstop3h 07m
Frontier
Deal found 4/23![Frontier logo]()
$187
This Cheapflightsfares deal was found by Cheapflights users on 4/22. 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 5/164:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sat 5/238:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/22![Frontier logo]()
$119
This Frontier deal was found by Cheapflights users on 4/22. 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.
Sun 5/246:30 am
DEN
- STL
1 stop10h 03m
Frontier
Sat 6/68:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/22![Frontier logo]()
$130
This Kiwi.com deal was found by Cheapflights users on 4/22. 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 5/2411:54 pm
DEN
- STL
1 stop8h 01m
Frontier
Mon 6/18:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/22![Frontier logo]()
$132
This Cheapflightsfares deal was found by Cheapflights users on 4/26. Clicking the “Pick Dates” 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 4/26![Allegiant Air logo]()
$149
This Frontier deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” 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 5/264:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Tue 6/28:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/23![Frontier logo]()
$128
This Cheapflightsfares deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Mon 6/19:21 pm
STL
- DEN
1 stop21h 43m
Frontier
Deal found 4/27![Frontier logo]()
$117
This Cheapflightsfares deal was found by Cheapflights users on 4/22. 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.
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Wed 6/36:51 pm
STL
- DEN
1 stop9h 34m
Frontier
Deal found 4/22![Frontier logo]()
$123
This Frontier deal was found by Cheapflights users on 4/22. 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.
Wed 5/274:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Fri 5/299:06 pm
STL
- DEN
1 stop7h 19m
Frontier
Deal found 4/22![Frontier logo]()
$124
This Frontier deal was found by Cheapflights users on 4/22. 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.
Thu 5/284:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sat 6/68:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/22![Frontier logo]()
$120
This Kiwi.com deal was found by Cheapflights users on 4/22. 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.
Thu 5/284:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Sat 5/308:08 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 4/22![Frontier logo]()
$122
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 27, 2026.
Search for one-way flight options from Denver to Illinois. Find affordable one-way fares based on user searches. Data last updated April 27, 2026.
This Kiwi.com deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” 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 5/114:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/23![Frontier logo]()
$49
This Kiwi.com deal was found by Cheapflights users on 4/23. Clicking the “Pick Dates” 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 5/164:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/23![Frontier logo]()
$59
This Kiwi.com deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/34:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/27![Frontier logo]()
$63
This Frontier deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 5/264:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/27![Frontier logo]()
$64
This Frontier deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 6/274:12 pm
DEN
- STL
Nonstop2h 11m
Frontier
Deal found 4/27![Frontier logo]()
$69
This Cheapflightsfares deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure 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 4/27![Frontier logo]()
$70
This Super.com deal was found by Cheapflights users on 4/22. 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.
Mon 5/187:01 pm
DEN
- STL
1 stop22h 05m
Frontier
Deal found 4/22![Frontier logo]()
$75
This Super.com deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Super.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 5/234:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/27![Frontier logo]()
$79
This Cheapflightsfares deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure 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
Deal found 4/27![Frontier logo]()
$80
This Booking.com deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 6/44:15 pm
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 4/27![Frontier logo]()
$81
This Kiwi.com deal was found by Cheapflights users on 4/27. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 6/235:05 pm
DEN
- ORD
Nonstop2h 38m
Frontier
Deal found 4/27![Frontier logo]()
$87
This Kiwi.com deal was found by Cheapflights users on 4/22. 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.
Mon 6/810:29 pm
DEN
- ORD
1 stop30h 03m
Frontier
Deal found 4/22![Frontier logo]()
$88
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 27, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $117 (Cheapflightsfares) |
One-way from | $49 (Kiwi.com) |
Popular in | March |
Cheapest in | August |
Average price | $291 |
Good round-trip deal | $275 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 27, 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
Wed 5/20
6:35 am-9:55 am
Nonstop2h 20m
Chicago Midway
Tue 5/26
8:50 pm-10:35 pm
Nonstop2h 45m
$201
DenverSt. Louis
DEN - STL
DENSTL
Denver Intl
Wed 5/20
5:34 pm-8:43 pm
Nonstop2h 09m
Lambert-St Louis
Wed 5/27
4:48 pm-6:23 pm
Nonstop2h 35m
$219
Quickest round-trip
DenverSt. Louis
DEN - STL
DENSTL
Denver Intl
Wed 5/20
5:55 am-9:00 am
Nonstop2h 05m
Lambert-St Louis
Wed 5/27
8:45 pm-10:05 pm
Nonstop2h 20m
$219
DenverChicago
DEN - ORD
DENORD
Denver Intl
Wed 6/10
5:45 am-12:36 pm
1 stop5h 51m
Chicago O'Hare Intl
Wed 6/17
5:57 pm-11:31 pm
1 stop6h 34m
$221
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Mon 6/1
6:05 am-12:42 pm
1 stop5h 37m
Chicago Midway
Sat 6/6
1:59 pm-8:15 pm
1 stop7h 16m
$225
DenverSt. Louis
DEN - STL
DENSTL
Denver Intl
Wed 5/20
10:05 am-1:13 pm
Nonstop2h 08m
Lambert-St Louis
Wed 5/20
5:59 pm-7:32 pm
Nonstop2h 33m
$227
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Sat 6/6
9:49 am-4:35 pm
1 stop5h 46m
Chicago Midway
Tue 6/16
6:05 am-11:07 am
1 stop6h 02m
$231
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Wed 6/24
10:15 am-4:50 pm
1 stop5h 35m
Chicago Midway
Tue 6/30
5:30 am-7:05 am
Nonstop2h 35m
$233
DenverPeoria
DEN - PIA
DENPIA
Denver Intl
Thu 5/28
4:27 pm-7:30 pm
Nonstop2h 03m
Greater Peoria
Sun 5/31
9:06 pm-8:08 am
1 stop12h 02m
$243
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Sat 5/23
5:45 pm-9:20 pm
Nonstop2h 35m
Chicago Midway
Wed 6/3
12:20 pm-5:20 pm
1 stop6h 00m
$243
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-ORD
DEN-MDW
DEN-PIA
DEN-RFD
DEN-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 Denver to Illinois
DEN-USIL
DEN-ORD
DEN-MDW
DEN-PIA
DEN-RFD
How far ahead should I book a flight from Denver to Illinois?
To ensure you get the cheapest price possible for a flight from Denver to Illinois, you should look to book at least 78 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.
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 27, 2026.
It’s optimal to fly from Denver to Illinois in the morning. By choosing this option you can save up to 25% 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. Sunday afternoons 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 27, 2026.
The most flights from DEN to USIL are scheduled on a Monday (65 on average). You will have fewer flight options on Thursday, which is when the least amount of flights are scheduled (30 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 27, 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.
Crew
8.6
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Food
7.0
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Crew
8.6
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Food
7.0
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Crew
8.6
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Food
7.0
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Crew
8.6
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Food
7.0
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Crew
8.6
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Food
7.0
Overall
8.0
Reviews
1 / 20
2.0
MediocreDominic,Mar 2026
MCO - SMF
Crew
8.6
Boarding
8.1
Comfort
8.0
Entertainment
7.5
Food
7.0
Overall
8.0
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
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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 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 27, 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 27, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$54 | Average$146 | 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$274 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$159 | Average$398 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$169 | Average$363 | FlexibilityNo cancel fee | On-time69% |