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$61+ Cheap flights from Ontario (ONT) 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 8/21. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — ORD
Jul 8 — Jul 151
Tue 7/8
Tue 7/15
1 adult, Economy
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Cheap flight deals from Ontario to Illinois

Keep the following information in mind while searching for Ontario to Illinois flight deals. Data was last updated July 3, 2025.

Round-trip from

$173
(Priceline)

One-way from

$61
(Priceline)

Popular in

December

Cheapest in

February

Average price

$301

Good round-trip deal

$422 or less

Good one-way deal

$218 or less
From Ontario to Illinois
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One-way flight from Ontario to Illinois
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Highest demand for flights based on searches. 7% potential increase in price ($24 potential increase over avg. RT price).
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Cheapest flight prices on average. 1% potential price decrease ($4 potential savings vs. average RT price).
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Average for round-trip flights in July 2025
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Price to beat on a round-trip flight from Ontario to Illinois.
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Price to beat on a one-way flight from Ontario to Illinois.
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Find flight deals from Ontario to Illinois

Cheapest flights from Ontario to Illinois
Explore the most affordable flight options available from Ontario to Illinois. Find the lowest fares from popular airlines and budget airlines, with prices last updated on July 3, 2025.

This Priceline deal was found by Cheapflights users on 7/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 7/46:00 amONT - STL
1 stop5h 42mFrontier
Sat 7/57:29 pmSTL - ONT
1 stop6h 21mFrontier
Deal found 7/1$172
This Orbitz deal was found by Cheapflights users on 7/2. 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 Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 7/246:00 amONT - MDW
2 stops12h 54mFrontier
Sat 7/262:44 pmMDW - ONT
1 stop11h 06mFrontier
Deal found 7/2$263
This FlightHub deal was found by Cheapflights users on 7/3. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/212:59 amONT - ORD
1 stop18h 43mFrontier
Fri 9/59:47 pmORD - ONT
1 stop16h 56mFrontier
Deal found 7/3$263
This American Airlines deal was found by Cheapflights users on 7/1. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 8/412:59 amONT - ORD
1 stop8h 00mAmerican Airlines
Tue 8/52:20 pmORD - ONT
1 stop5h 48mAmerican Airlines
Deal found 7/1$277
This American Airlines deal was found by Cheapflights users on 7/3. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/2112:47 pmONT - MLI
1 stop8h 35mAmerican Airlines
Sun 8/246:20 amMLI - ONT
1 stop7h 33mAmerican Airlines
Deal found 7/3$289
This American Airlines deal was found by Cheapflights users on 7/3. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/222:57 pmONT - PIA
1 stop6h 19mAmerican Airlines
Mon 8/255:09 pmPIA - ONT
1 stop7h 39mAmerican Airlines
Deal found 7/3$289
This Southwest deal was found by Cheapflights users on 7/1. Clicking the “Pick Dates” 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 8/145:40 amONT - MDW
1 stop8h 45mSouthwest
Thu 8/218:20 pmMDW - ONT
Nonstop4h 10mSouthwest
Deal found 7/1$307
This Delta deal was found by Cheapflights users on 7/2. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/1412:00 pmONT - MDW
1 stop7h 44mDelta
Tue 10/216:00 amMDW - ONT
1 stop7h 24mDelta
Deal found 7/2$317
This Trip.com deal was found by Cheapflights users on 7/3. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/167:00 amONT - MLI
1 stop26h 46mMultiple Airlines
Thu 7/2412:36 pmMLI - ONT
1 stop10h 16mMultiple Airlines
Deal found 7/3$356
This Delta deal was found by Cheapflights users on 7/3. 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 8/111:40 amONT - MLI
1 stop8h 39mDelta
Fri 8/85:26 pmMLI - ONT
1 stop7h 01mDelta
Deal found 7/3$374
This United Airlines deal was found by Cheapflights users on 7/3. 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.
Thu 12/251:00 pmONT - MLI
1 stop6h 03mUnited Airlines
Thu 1/13:52 pmMLI - ONT
1 stop8h 34mUnited Airlines
Deal found 7/3$379
This United Airlines deal was found by Cheapflights users on 7/1. Clicking the “Pick Dates” 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 11/117:00 amONT - PIA
1 stop7h 40mUnited Airlines
Sat 11/223:30 pmPIA - ONT
1 stop9h 01mUnited Airlines
Deal found 7/1$379

Cheapflights Fare Finder

Customize your flight search to find flights from Ontario 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 July 3, 2025.
Use the filters below to find and compare flights from Ontario to Illinois that are best for you.

Fly from

Ontario

Fly to

Illinois

Route

Depart

Return

Price

OntarioSt. Louis

ONT - STL

ONTSTL

Ontario

Fri 9/5

8:59 pm-9:06 am

1 stop10h 07m

Lambert-St Louis

Sun 9/7

10:39 am-3:24 pm

1 stop6h 45m

$173

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Thu 7/24

6:00 am-8:54 pm

2 stops12h 54m

Chicago Midway

Sat 7/26

2:44 pm-11:50 pm

1 stop11h 06m

$263

OntarioChicago

ONT - ORD

ONTORD

Ontario

Tue 9/2

12:59 am-9:42 pm

1 stop18h 43m

Chicago O'Hare Intl

Fri 9/5

9:47 pm-12:43 pm

1 stop16h 56m

$263

OntarioChicago

ONT - ORD

ONTORD

Ontario

Mon 8/4

12:59 am-10:59 am

1 stop8h 00m

Chicago O'Hare Intl

Tue 8/5

2:20 pm-6:08 pm

1 stop5h 48m

$277

OntarioMoline

ONT - MLI

ONTMLI

Ontario

Thu 8/21

12:47 pm-11:22 pm

1 stop8h 35m

Moline Quad-City

Sun 8/24

6:20 am-11:53 am

1 stop7h 33m

$289

OntarioPeoria

ONT - PIA

ONTPIA

Ontario

Fri 8/22

2:57 pm-11:16 pm

1 stop6h 19m

Greater Peoria

Mon 8/25

5:09 pm-10:48 pm

1 stop7h 39m

$289

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Thu 8/14

5:40 am-4:25 pm

1 stop8h 45m

Chicago Midway

Tue 8/19

5:25 pm-7:35 pm

Nonstop4h 10m

$307

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Wed 8/13

11:45 am-9:44 pm

1 stop7h 59m

Chicago Midway

Thu 8/21

12:43 pm-7:11 pm

1 stop8h 28m

$317

OntarioMoline

ONT - MLI

ONTMLI

Ontario

Wed 7/16

7:00 am-11:46 am

1 stop26h 46m

Moline Quad-City

Thu 7/24

12:36 pm-8:52 pm

1 stop10h 16m

$356

OntarioMoline

ONT - MLI

ONTMLI

Ontario

Fri 8/1

11:40 am-10:19 pm

1 stop8h 39m

Moline Quad-City

Fri 8/8

5:26 pm-10:27 pm

1 stop7h 01m

$374

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/2

Showing 1-10 of 30 results
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2
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Best time to book a flight from Ontario to Illinois

Have a flexible travel schedule? Discover the best time to fly to Illinois from Ontario with our price prediction graph.
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 Ontario to Illinois

What is the cheapest month to book a flight from Ontario to Illinois?

Currently, August is the cheapest month in which you can book a flight from Ontario to Illinois (average of $245). Flying from Ontario to Illinois in March is currently the most expensive (average of $321). 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 ONT to IL?

Find hourly flight availability from Ontario 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 July 3, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Ontario to Illinois as you normally would.

How much does it cost to fly round-trip from Ontario 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 July 3, 2025.
Read through reviews of airlines operating flights from Ontario to Illinois, such as Alaska Airlines, Southwest, and Delta. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
10,000 reviews

Overall

8.0

Comfort

7.8

Food

7.1

Crew

8.5

Boarding

8.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Overall

8.0

Comfort

7.8

Food

7.1

Crew

8.5

Boarding

8.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Southwest
8.0
Very good
4,266 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Overall

8.0

Comfort

7.8

Food

7.1

Crew

8.5

Boarding

8.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
Delta
8.0
Very good
7,982 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Overall

8.0

Comfort

7.8

Food

7.1

Crew

8.5

Boarding

8.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
United Airlines
7.4
Good
8,861 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Overall

8.0

Comfort

7.8

Food

7.1

Crew

8.5

Boarding

8.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.
American Airlines
7.2
Good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Overall

8.0

Comfort

7.8

Food

7.1

Crew

8.5

Boarding

8.1

Entertainment

7.1

Reviews

1 / 20
10.0
Excellent

James,Apr 2025

LAX - SFO

Good flight except the uncontrollable cold air from the ceiling.

Related info for your journey

Find useful and relevant information for your journey from Ontario to Illinois. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly from for flights from Ontario to Illinois?

    Ontario (ONT), located 3.1 mi from the city center, is the airport you fly out of when you book flights from Ontario to Illinois.

  • What are the cheapest airlines to fly from Ontario to Illinois one-way?

    $61 is the cheapest one-way deal found within the past few days, from Frontier. You may also be able to find cheap deals on Southwest and Alaska Airlines, with prices starting from $149 and $159, respectively.

  • What are the most popular routes from Ontario to Illinois?

    The most popular flight routes from Ontario to Illinois are Ontario - Chicago O'Hare Intl, Ontario - Chicago Midway and Ontario - Lambert-St Louis.

  • What are the cheapest flights from Ontario to Illinois?

    While on average a flight from Ontario to Illinois is generally $680, our data shows the cheapest flight currently is $174. When looking at the most popular route, (Ontario - Chicago O'Hare Intl), you can expect to pay $237 for that flight.

  • Can I find deals for flights from Ontario to Illinois that include hotel bookings?

    Yes. In addition to deals on Ontario to Illinois flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Ontario to Illinois?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Ontario to Illinois.

  • Can I find deals for business class flights from Ontario to Illinois?

    Yes. Cheapflights offers flight deals from Ontario to Illinois by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Ontario to Illinois?

    Currently, August is the cheapest month in which you can book a flight from Ontario to Illinois (average of $245). Flying from Ontario to Illinois in March is currently the most expensive (average of $321). 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.

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Alternative routes for Ontario to Illinois

See prices for flight routes from nearby airports that may be better suited for you.
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Top 6 airlines flying from Ontario to Illinois

Discover the top 6 airlines that operate flights from Ontario 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 July 3, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$99Average$217FlexibilityNo cancel feeOn-time65%
FrontierCheapest$108Average$179FlexibilityNo cancel feeOn-time62%
DeltaCheapest$173Average$391FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$227Average$488FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$237Average$443FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$246Average$522FlexibilityNo cancel feeOn-time71%

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