$42+ 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 5/4. Fares are subject to change and may not be available on all flights or dates of travel.
DEN — ORD
Apr 6 — Apr 131
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 7, 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 7, 2026.
This Cheapflightsfares deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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.
Mon 3/166:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Wed 3/258:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$87
This Cheapflightsfares deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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
Fri 5/88:12 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/4![Frontier logo]()
$88
This Cheapflightsfares deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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.
Mon 4/136:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Sat 4/188:17 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/4![Frontier logo]()
$92
This Frontier deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 3/286:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Mon 3/308:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$96
This Frontier deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” 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 3/256:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Sat 3/288:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/3![Frontier logo]()
$97
This Frontier deal was found by Cheapflights users on 3/5. Clicking the “Pick Dates” 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 4/304:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Sun 5/38:06 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/5![Frontier logo]()
$98
This Kiwi.com deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 3/286:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Sat 3/288:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$99
This Frontier deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 3/166:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Sat 3/288:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$104
This Kiwi.com deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” 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 3/276:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Sat 3/288:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/3![Frontier logo]()
$106
This Cheapflightsfares deal was found by Cheapflights users on 3/2. Clicking the “Pick Dates” 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.
Mon 4/66:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Wed 4/88:16 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/2![Frontier logo]()
$107
This Frontier deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 3/166:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Mon 3/238:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$108
This Frontier deal was found by Cheapflights users on 3/2. Clicking the “Pick Dates” 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 4/1010:40 pm
DEN
- STL
1 stop12h 41m
Frontier
Mon 4/138:19 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/2![Frontier logo]()
$109
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 7, 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 7, 2026.
This United Airlines deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” 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 3/315:45 pm
DEN
- STL
Nonstop2h 09m
United Airlines
Tue 4/78:54 am
STL
- DEN
Nonstop2h 33m
United Airlines
Deal found 3/3![United Airlines logo]()
$177
This Southwest deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 4/116:30 am
DEN
- MDW
Nonstop2h 20m
Southwest
Mon 4/136:00 am
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 3/6![Southwest logo]()
$198
This Delta deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/1012:35 am
DEN
- ORD
1 stop7h 35m
Delta
Mon 4/1311:00 am
ORD
- DEN
1 stop7h 21m
Delta
Deal found 3/6![Delta logo]()
$221
This American Airlines deal was found by Cheapflights users on 3/2. Clicking the “Pick Dates” 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 5/55:44 pm
DEN
- BMI
1 stop5h 08m
American Airlines
Tue 5/1211:16 am
BMI
- DEN
1 stop6h 46m
American Airlines
Deal found 3/2![American Airlines logo]()
$229
This Kiwi.com deal was found by Cheapflights users on 3/5. Clicking the “Pick Dates” 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 5/611:59 pm
DEN
- EVV
2 stops30h 04m
Multiple Airlines
Wed 5/134:29 pm
EVV
- DEN
1 stop16h 52m
Multiple Airlines
Deal found 3/5![Multiple Airlines logo]()
$243
This United Airlines deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” 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 4/185:45 pm
DEN
- STL
Nonstop2h 09m
United Airlines
Sat 4/258:54 am
STL
- DEN
Nonstop2h 33m
United Airlines
Deal found 3/3![United Airlines logo]()
$197
This Southwest deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 6/311:45 am
DEN
- MDW
1 stop3h 55m
Southwest
Mon 6/85:15 am
MDW
- DEN
Nonstop2h 35m
Southwest
Deal found 3/6![Southwest logo]()
$204
This United Airlines deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 6/34:20 pm
DEN
- ORD
Nonstop2h 45m
United Airlines
Mon 6/85:00 am
ORD
- DEN
Nonstop2h 42m
United Airlines
Deal found 3/6![United Airlines logo]()
$198
This Southwest deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 4/218:40 am
DEN
- STL
1 stop3h 20m
Southwest
Tue 4/283:55 pm
STL
- DEN
Nonstop2h 25m
Southwest
Deal found 3/6![Southwest logo]()
$207
This Delta deal was found by Cheapflights users on 3/5. Clicking the “Pick Dates” 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 3/5![Delta logo]()
$249
This American Airlines deal was found by Cheapflights users on 3/2. Clicking the “Pick Dates” 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 4/1711:46 am
DEN
- MLI
1 stop9h 19m
American Airlines
Sun 4/196:41 pm
MLI
- DEN
1 stop6h 18m
American Airlines
Deal found 3/2![American Airlines logo]()
$249
This Southwest deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/175:35 pm
DEN
- MDW
Nonstop2h 30m
Southwest
Sun 4/196:55 am
MDW
- DEN
2 stops6h 35m
Southwest
Deal found 3/3![Southwest logo]()
$208
This Southwest deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 5/78:20 pm
DEN
- MDW
Nonstop2h 20m
Southwest
Sun 5/106:00 am
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 3/6![Southwest logo]()
$209
This United Airlines deal was found by Cheapflights users on 3/5. Clicking the “Pick Dates” 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 5/285:38 pm
DEN
- MLI
Nonstop2h 16m
United Airlines
Tue 6/23:52 pm
MLI
- DEN
1 stop7h 07m
United Airlines
Deal found 3/5![United Airlines logo]()
$239
This Delta deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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 4/187:00 am
DEN
- BMI
1 stop7h 37m
Delta
Fri 4/244:20 pm
BMI
- DEN
1 stop9h 16m
Delta
Deal found 3/4![Delta logo]()
$269
This Kiwi.com deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 5/19:25 am
DEN
- EVV
1 stop8h 41m
Multiple Airlines
Mon 5/47:46 pm
EVV
- DEN
1 stop28h 13m
Multiple Airlines
Deal found 3/6![Multiple Airlines logo]()
$298
This Southwest deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” 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 4/116:30 am
DEN
- MDW
Nonstop2h 20m
Southwest
Sun 4/196:00 am
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 3/3![Southwest logo]()
$217
This United Airlines deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” 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 3/275:31 pm
DEN
- MLI
Nonstop2h 17m
United Airlines
Sat 4/48:54 am
MLI
- DEN
Nonstop2h 39m
United Airlines
Deal found 3/3![United Airlines logo]()
$240
This Kiwi.com deal was found by Cheapflights users on 3/2. Clicking the “Pick Dates” 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 4/3010:35 pm
DEN
- RFD
1 stop20h 10m
Multiple Airlines
Thu 5/710:37 am
RFD
- DEN
2 stops22h 32m
Multiple Airlines
Deal found 3/2![Multiple Airlines logo]()
$313
This United Airlines deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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 6/47:40 pm
DEN
- ORD
Nonstop2h 39m
United Airlines
Sun 6/710:55 pm
ORD
- DEN
Nonstop2h 58m
United Airlines
Deal found 3/4![United Airlines logo]()
$245
This Southwest deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 6/36:15 am
DEN
- ORD
1 stop6h 00m
Southwest
Mon 6/88:05 pm
ORD
- DEN
1 stop12h 55m
Southwest
Deal found 3/6![Southwest logo]()
$223
This Delta deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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 4/187:00 am
DEN
- MLI
1 stop8h 28m
Delta
Fri 4/245:11 pm
MLI
- DEN
1 stop8h 25m
Delta
Deal found 3/4![Delta logo]()
$304
This Kiwi.com deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 6/410:35 pm
DEN
- RFD
1 stop20h 45m
Multiple Airlines
Sun 6/149:19 am
RFD
- DEN
1 stop13h 11m
Multiple Airlines
Deal found 3/6![Multiple Airlines logo]()
$315
This Southwest deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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 4/1811:40 am
DEN
- MDW
1 stop4h 35m
Southwest
Sat 4/255:30 pm
MDW
- DEN
Nonstop2h 40m
Southwest
Deal found 3/4![Southwest logo]()
$223
This United Airlines deal was found by Cheapflights users on 3/5. Clicking the “Pick Dates” 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 3/266:00 am
DEN
- PIA
1 stop6h 45m
United Airlines
Thu 4/27:43 pm
PIA
- DEN
1 stop5h 16m
United Airlines
Deal found 3/5![United Airlines logo]()
$249
This United Airlines deal was found by Cheapflights users on 3/5. Clicking the “Pick Dates” 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 4/177:45 am
DEN
- PIA
1 stop5h 23m
United Airlines
Sun 4/197:43 pm
PIA
- DEN
1 stop6h 15m
United Airlines
Deal found 3/5![United Airlines logo]()
$249
This Southwest deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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 5/14:00 pm
DEN
- ORD
1 stop6h 55m
Southwest
Mon 5/46:15 pm
ORD
- DEN
Nonstop2h 50m
Southwest
Deal found 3/4![Southwest logo]()
$227
This American Airlines deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 4/287:36 am
DEN
- SPI
1 stop5h 43m
American Airlines
Mon 5/45:45 am
SPI
- DEN
1 stop5h 12m
American Airlines
Deal found 3/6![American Airlines logo]()
$407
This Delta deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 4/1711:55 pm
DEN
- BMI
2 stops21h 26m
Delta
Mon 4/204:20 pm
BMI
- DEN
1 stop9h 16m
Delta
Deal found 3/3![Delta logo]()
$353
This Southwest deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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
Fri 4/243:35 pm
MDW
- DEN
1 stop5h 25m
Southwest
Deal found 3/4![Southwest logo]()
$227
Last-minute flights from Denver to IllinoisDiscover last-minute flight deals from Denver to Illinois. Data last updated March 7, 2026 and is based on user searches.
Discover last-minute flight deals from Denver to Illinois. Data last updated March 7, 2026 and is based on user searches.
This Cheapflightsfares deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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.
Mon 3/166:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Wed 3/258:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$87
This Frontier deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 3/166:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Sat 3/288:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$104
This Frontier deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 3/166:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Mon 3/238:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$108
This Frontier deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” 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 3/256:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Sat 3/288:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/3![Frontier logo]()
$97
This Kiwi.com deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” 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 3/276:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Sat 3/288:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/3![Frontier logo]()
$106
This Frontier deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 3/286:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Mon 3/308:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$96
This Kiwi.com deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 3/286:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Sat 3/288:12 pm
STL
- DEN
Nonstop2h 37m
Frontier
Deal found 3/6![Frontier logo]()
$99
This Cheapflightsfares deal was found by Cheapflights users on 3/2. Clicking the “Pick Dates” 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.
Mon 4/66:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Wed 4/88:16 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/2![Frontier logo]()
$107
This Frontier deal was found by Cheapflights users on 3/2. Clicking the “Pick Dates” 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 4/1010:40 pm
DEN
- STL
1 stop12h 41m
Frontier
Mon 4/138:19 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/2![Frontier logo]()
$109
This Cheapflightsfares deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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.
Mon 4/136:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Sat 4/188:17 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/4![Frontier logo]()
$92
This Kiwi.com deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/136:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Mon 4/208:17 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/6![Frontier logo]()
$111
This Frontier deal was found by Cheapflights users on 3/5. Clicking the “Pick Dates” 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 4/304:09 pm
DEN
- STL
Nonstop2h 12m
Frontier
Sun 5/38:06 pm
STL
- DEN
Nonstop2h 33m
Frontier
Deal found 3/5![Frontier logo]()
$98
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 7, 2026.
Search for one-way flight options from Denver to Illinois. Find affordable one-way fares based on user searches. Data last updated March 7, 2026.
This Kiwi.com deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 5/44:20 pm
DEN
- STL
Nonstop2h 12m
Frontier
Deal found 3/6![Frontier logo]()
$42
This Kiwi.com deal was found by Cheapflights users on 3/3. Clicking the “Pick Dates” 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 5/104:00 pm
DEN
- STL
Nonstop2h 12m
Frontier
Deal found 3/3![Frontier logo]()
$43
This Expedia deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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.
Sat 4/116:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 3/4![Frontier logo]()
$44
This Kiwi.com deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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
Deal found 3/6![Frontier logo]()
$45
This Frontier deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 5/74:00 pm
DEN
- STL
Nonstop2h 12m
Frontier
Deal found 3/6![Frontier logo]()
$46
This Kiwi.com deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 4/46:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 3/4![Frontier logo]()
$52
This Kiwi.com deal was found by Cheapflights users on 3/5. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 4/204:20 pm
DEN
- STL
Nonstop2h 12m
Frontier
Deal found 3/5![Frontier logo]()
$53
This Super.com deal was found by Cheapflights users on 3/2. Clicking the “Pick Dates” 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
Deal found 3/2![Frontier logo]()
$63
This Super.com deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” 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 4/36:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 3/4![Frontier logo]()
$64
This Super.com deal was found by Cheapflights users on 3/6. Clicking the “Pick Dates” 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 3/136:35 am
DEN
- STL
Nonstop2h 14m
Frontier
Deal found 3/6![Frontier logo]()
$68
This Expedia deal was found by Cheapflights users on 3/4. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Expedia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 4/86:40 am
DEN
- STL
Nonstop2h 08m
Frontier
Deal found 3/4![Frontier logo]()
$69
This Flightnetwork deal was found by Cheapflights users on 3/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Flightnetwork is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 3/169:19 pm
DEN
- ORD
Nonstop2h 38m
Frontier
Deal found 3/2![Frontier logo]()
$84
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 7, 2026.
Most accurate provider | FlightHub 3 stars |
|---|---|
Most trusted provider | FlightHub 3 stars |
Round-trip from | $87 (Cheapflightsfares) |
One-way from | $42 (Kiwi.com) |
Popular in | November |
Cheapest in | August |
Average price | $225 |
Good round-trip deal | $263 or less |
Good one-way deal | $145 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 7, 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
Quickest round-trip
DenverSt. Louis
DEN - STL
DENSTL
Denver Intl
Tue 3/31
5:45 pm-8:54 pm
Nonstop2h 09m
Lambert-St Louis
Tue 4/7
8:54 am-10:27 am
Nonstop2h 33m
$177
DenverSt. Louis
DEN - STL
DENSTL
Denver Intl
Sat 4/18
5:45 pm-8:54 pm
Nonstop2h 09m
Lambert-St Louis
Sat 4/25
8:54 am-10:27 am
Nonstop2h 33m
$197
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Sat 4/11
6:30 am-9:50 am
Nonstop2h 20m
Chicago Midway
Mon 4/13
6:00 am-7:40 am
Nonstop2h 40m
$198
DenverChicago
DEN - ORD
DENORD
Denver Intl
Wed 6/3
4:20 pm-8:05 pm
Nonstop2h 45m
Chicago O'Hare Intl
Mon 6/8
5:00 am-6:42 am
Nonstop2h 42m
$198
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Wed 6/3
11:45 am-4:40 pm
1 stop3h 55m
Chicago Midway
Mon 6/8
5:15 am-6:50 am
Nonstop2h 35m
$204
DenverSt. Louis
DEN - STL
DENSTL
Denver Intl
Tue 4/21
8:40 am-1:00 pm
1 stop3h 20m
Lambert-St Louis
Tue 4/28
3:55 pm-5:20 pm
Nonstop2h 25m
$207
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Fri 4/17
5:35 pm-9:05 pm
Nonstop2h 30m
Chicago Midway
Sun 4/19
6:55 am-12:30 pm
2 stops6h 35m
$208
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Thu 5/7
8:20 pm-11:40 pm
Nonstop2h 20m
Chicago Midway
Sun 5/10
6:00 am-7:40 am
Nonstop2h 40m
$209
DenverChicago
DEN - MDW
DENMDW
Denver Intl
Sat 4/11
6:30 am-9:50 am
Nonstop2h 20m
Chicago Midway
Sun 4/19
6:00 am-7:40 am
Nonstop2h 40m
$217
DenverChicago
DEN - ORD
DENORD
Denver Intl
Fri 4/10
12:35 am-9:10 am
1 stop7h 35m
Chicago O'Hare Intl
Mon 4/13
11:00 am-5:21 pm
1 stop7h 21m
$221
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-RFD
DEN-BMI
DEN-MDW
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-RFD
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 $110). 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 7, 2026.
It’s optimal to fly from Denver to Illinois in the morning. By choosing this option you can save up to 26% 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. Sunday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.
Reviews of airlines servicing Illinois
Get insights into the airlines that provide service to Illinois. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Illinois. Reviews last updated March 7, 2026.
Read through reviews of airlines operating flights from Denver to Illinois, such as Southwest, United Airlines, and Allegiant Air. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
Food
7.0
Boarding
8.1
Comfort
8.0
Overall
8.0
Entertainment
7.5
Crew
8.6
Reviews
1 / 20
10.0
ExcellentAnonymous,Mar 2026
KOA - HNL
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 7, 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 7, 2026.
| Airline | Cheapest | Average | Flexibility | On-time |
|---|---|---|---|---|
| Cheapest$57 | Average$141 | FlexibilityNo cancel fee | On-time88% | |
| Cheapest$70 | Average$184 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$126 | Average$191 | FlexibilityNo cancel fee | On-time62% | |
| Cheapest$155 | Average$265 | FlexibilityNo cancel fee | On-time63% | |
| Cheapest$157 | Average$408 | FlexibilityNo cancel fee | On-time71% | |
| Cheapest$159 | Average$358 | FlexibilityNo cancel fee | On-time69% |