Cheap Flights from Ontario International to Chicago

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Compare Ontario International to Chicago flight deals

Find the cheapest month or even day of the year to fly to Chicago

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Flight deals from Ontario International to Chicago

Looking for a cheap last-minute deal or the best return flight from Ontario International Airport to Chicago? If you want to travel next month, return fares start from $331. Find the lowest prices on one-way and return tickets right here.

Chicago.$331 per passenger.Departing Tue, 6 Oct, returning Wed, 14 Oct.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Tue, 6 Oct, arriving in Chicago O'Hare International.Inbound indirect flight with Frontier Airlines, departs from Chicago O'Hare International on Wed, 14 Oct, arriving in Ontario International.Price includes taxes and charges.From $331, select.

Chicago.$331 per passenger.Departing Wed, 4 Nov, returning Sat, 7 Nov.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Wed, 4 Nov, arriving in Chicago O'Hare International.Inbound indirect flight with Frontier Airlines, departs from Chicago O'Hare International on Sat, 7 Nov, arriving in Ontario International.Price includes taxes and charges.From $331, select.

Chicago.$331 per passenger.Departing Sat, 31 Oct, returning Sat, 14 Nov.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Sat, 31 Oct, arriving in Chicago O'Hare International.Inbound indirect flight with Frontier Airlines, departs from Chicago O'Hare International on Sat, 14 Nov, arriving in Ontario International.Price includes taxes and charges.From $331, select.

Chicago.$336 per passenger.Departing Wed, 18 Nov, returning Wed, 2 Dec.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Wed, 18 Nov, arriving in Chicago O'Hare International.Inbound indirect flight with Frontier Airlines, departs from Chicago O'Hare International on Wed, 2 Dec, arriving in Ontario International.Price includes taxes and charges.From $336, select.

Chicago.$340 per passenger.Departing Tue, 29 Sep, returning Mon, 5 Oct.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Tue, 29 Sep, arriving in Chicago O'Hare International.Inbound indirect flight with Frontier Airlines, departs from Chicago O'Hare International on Mon, 5 Oct, arriving in Ontario International.Price includes taxes and charges.From $340, select.

Chicago.$340 per passenger.Departing Wed, 16 Sep, returning Thu, 17 Sep.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Ontario International on Wed, 16 Sep, arriving in Chicago O'Hare International.Inbound indirect flight with Frontier Airlines, departs from Chicago O'Hare International on Thu, 17 Sep, arriving in Ontario International.Price includes taxes and charges.From $340, select.

Chicago.$405 per passenger.Departing Thu, 3 Dec, returning Sat, 5 Dec.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Ontario International on Thu, 3 Dec, arriving in Chicago Midway.Inbound direct flight with Southwest Airlines departs from Chicago Midway on Sat, 5 Dec, arriving in Ontario International.Price includes taxes and charges.From $405, select.

Chicago.$406 per passenger.Departing Thu, 25 Feb, returning Mon, 1 Mar.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Ontario International on Thu, 25 Feb, arriving in Chicago Midway.Inbound direct flight with Southwest Airlines departs from Chicago Midway on Mon, 1 Mar, arriving in Ontario International.Price includes taxes and charges.From $406, select.

Chicago.$406 per passenger.Departing Sat, 31 Oct, returning Sat, 14 Nov.Return flight with United.Outbound direct flight with United departs from Ontario International on Sat, 31 Oct, arriving in Chicago O'Hare International.Inbound direct flight with United departs from Chicago O'Hare International on Sat, 14 Nov, arriving in Ontario International.Price includes taxes and charges.From $406, select.

Chicago.$406 per passenger.Departing Sat, 13 Feb, returning Tue, 16 Feb.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Ontario International on Sat, 13 Feb, arriving in Chicago Midway.Inbound direct flight with Southwest Airlines departs from Chicago Midway on Tue, 16 Feb, arriving in Ontario International.Price includes taxes and charges.From $406, select.

Chicago.$406 per passenger.Departing Sat, 14 Nov, returning Tue, 17 Nov.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Ontario International on Sat, 14 Nov, arriving in Chicago Midway.Inbound direct flight with Southwest Airlines departs from Chicago Midway on Tue, 17 Nov, arriving in Ontario International.Price includes taxes and charges.From $406, select.

Chicago.$406 per passenger.Departing Sat, 17 Oct, returning Sat, 31 Oct.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Ontario International on Sat, 17 Oct, arriving in Chicago Midway.Inbound direct flight with Southwest Airlines departs from Chicago Midway on Sat, 31 Oct, arriving in Ontario International.Price includes taxes and charges.From $406, select.

Chicago.$423 per passenger.Departing Tue, 5 Jan, returning Sat, 9 Jan.Return flight with United.Outbound indirect flight with United, departs from Ontario International on Tue, 5 Jan, arriving in Chicago O'Hare International.Inbound indirect flight with United, departs from Chicago O'Hare International on Sat, 9 Jan, arriving in Ontario International.Price includes taxes and charges.From $423, select.

Chicago.$433 per passenger.Departing Sat, 26 Sep, returning Fri, 2 Oct.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Ontario International on Sat, 26 Sep, arriving in Chicago Midway.Inbound direct flight with Southwest Airlines departs from Chicago Midway on Fri, 2 Oct, arriving in Ontario International.Price includes taxes and charges.From $433, select.

Chicago.$439 per passenger.Departing Thu, 7 Jan, returning Sun, 10 Jan.Return flight with Southwest Airlines.Outbound direct flight with Southwest Airlines departs from Ontario International on Thu, 7 Jan, arriving in Chicago Midway.Inbound direct flight with Southwest Airlines departs from Chicago Midway on Sun, 10 Jan, arriving in Ontario International.Price includes taxes and charges.From $439, select.

Chicago.$453 per passenger.Departing Mon, 1 Mar, returning Wed, 10 Mar.Return flight with United.Outbound indirect flight with United, departs from Ontario International on Mon, 1 Mar, arriving in Chicago O'Hare International.Inbound indirect flight with United, departs from Chicago O'Hare International on Wed, 10 Mar, arriving in Ontario International.Price includes taxes and charges.From $453, select.

Find the cheapest month to fly from Ontario International to Chicago

We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like Ontario International to Chicago flights are currently cheapest in October.

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Direct flights from Ontario International to Chicago

Alternative Ontario International to Chicago routes

Looking for the cheapest, fastest or easiest route from Ontario International to Chicago? You could fly into the following airports instead.

Ontario to Chicago: Flight information

The things to know before you go.

Cheapest flight found	$331
Cheapest month to fly	October
Average flight time	3 hrs, 58 mins
Most popular airline	American Airlines
Average flights per week	24

Finding cheap flights from Ontario International to Chicago: Frequently asked questions

How many airports are there in Chicago?

There are 3 airports in Chicago: Chicago Midway, Chicago O'Hare International and Chicago Rockford.

How much are return flights from Ontario International to Chicago?

The best price we found for a return flight from Ontario International to Chicago is $331. This is an estimate based on information collected from different airlines and travel providers over the last 4 days and is subject to change and availability.

How long does it take to fly from Ontario International to Chicago?

3 hours and 57 minutes is the average flight time from Ontario International to Chicago.

Which airlines fly direct from Ontario International to Chicago?

American Airlines, Southwest Airlines and United fly direct from Ontario International to Chicago.

How many flights are there a week from Ontario International to Chicago?

As of September 2026, there are 24 flights per week flying from Ontario International to Chicago.

When is the cheapest time to fly from Ontario International to Chicago?

The cheapest month to fly from Ontario International to Chicago is usually October.

Which is the cheapest airport to fly into in Chicago?

If you're flying from Ontario International Airport, the cheapest airport near Chicago is Chicago O'Hare International – which is 25.5 km away from the centre of Chicago. We've found flights into this airport from $331.

Which upcoming date is cheapest to fly from Ontario International Airport to Chicago on?

After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Ontario International Airport to Chicago on Tuesday, 6 October 2026.

Can I get a direct flight from Ontario International Airport to Chicago?

Yes – the average flight time is 3 hours and 57 minutes.

How can I get the best flight deal from Ontario International Airport to Chicago?

We show every price from over 1,200 airlines and travel agents, comparing them all so you don’t have to. If you know you want to fly to Chicago but you’re not ready to book, set up a Price Alert. We’ll track prices for you, and let you know when they rise or fall.

When is the best time to book flights to Chicago?

We crunched all the numbers in our flight calendar and it looks like the cheapest time to book a flight to Chicago is around 40 days in advance, so don’t leave your flight to the last minute.

What’s the weather like in Chicago?

In September, the average temperature is usually around 20°C. July is typically the warmest month in Chicago, when it usually averages around 27°C. You can expect the least rain in February. The coldest month is January, with temperatures averaging -5°C. The rainiest month is June.

Which is the cheapest airline to fly from Ontario International Airport to Chicago with?

Currently, Frontier Airlines and Southwest Airlines offer the cheapest flight tickets to Chicago.

Travelling from Ontario International Airport (ONT) to Chicago: what you need to know

Expect to be in the air for 4 hours 30 minutes. On average, that's the duration of a direct flight from Ontario International Airport to Chicago.
Chicago is two hours ahead of Ontario, where Ontario International Airport is located. Chicago runs on the UTC-6 timezone.
Ontario International Airport (ONT) to Chicago O'Hare International Airport (ORD) is the most popular route, with five departures a week to choose from. You can fly from ONT to ORD at 07:00 with United Airlines.
For a stress-free journey, arrive at the airport two hours ahead of international flights and one hour before domestic departures. This will give you enough time to catch your ONT to Chicago flight.
Travelling during a peak month such as July? Public holidays and other high seasons can lead to longer lines at security. Play it safe and arrive up to four hours before an international flight and two hours before a domestic departure.
Direct Ontario International Airport to Chicago tickets are available for booking. Chicago O'Hare International Airport (ORD) will be your arrival point.
Take to the skies with United Airlines. This popular carrier operates direct flights from Ontario International Airport to Chicago.
ONT is about 5 kilometres from central Ontario. If you're catching a taxi, ride-sharing or driving from the centre, it'll take you 15 minutes or so to get there, depending on traffic. If you're taking public transport, expect the travel time to be around 45 minutes.
Planning to catch an early flight from Ontario International Airport to Chicago? Avoid rushing to the airport (and sneak in some extra snooze time) by choosing one of these hotels near ONT:
Ontario International Airport maintains a strong on-time record, reducing the likelihood of delays. Departures from ONT land on schedule 83% of the time.
You'll find ONT at 2900 E. Airport Drive.

How to find the cheapest flights from Ontario International Airport (ONT) to Chicago

$160 is the lowest price we've seen for a one-way Ontario International Airport to Chicago flight. A round-trip plane ticket right now is $331. Depending on when and how early you book, these fares may change.
To secure cheap flights from ONT to Chicago, reserve your journey one month before your planned departure.
The best month for picking up cheap Ontario International Airport to Chicago tickets is June. Use the 'Whole month' tool to compare all available prices, then choose the dates that offer the biggest savings.
Spend less time searching for cheap flights from ONT to Chicago by creating a Price Alert. You'll get an email or notification on the app when fares go down.
Tailor your trip with filters. Select your preferred arrival and departure times, airlines and total journey duration. You can also sort your results by 'Best,' 'Cheapest' or 'Fastest' flights from Ontario International Airport to Chicago.

Airports in Chicago

Chicago O'Hare International Airport (ORD)

Chicago O'Hare International Airport (ORD) to the centre of Chicago takes around 30 minutes to reach by car. The centre is roughly 27 kilometres away.
It takes around 45 minutes if you're using public transport.
Consider booking a hotel close to ORD if you're coming in on a late flight from Ontario International Airport to Chicago. Settle into one of these accommodation options and make your first night all about rest:
To secure the lowest price, book your vehicle from Chicago O'Hare International Airport about four weeks ahead of your flight from ONT to Chicago.
ORD is located at 10000 West O'Hare.

Chicago Midway International Airport (MDW)

Once your flight from Ontario International Airport to Chicago has arrived, you can make your way to the city centre in around 25 minutes by car. Central Chicago is roughly 16 kilometres from Chicago Midway International Airport (MDW).
If you travel by public transport, the ride to the centre will take you 30 minutes or so.
Following your ONT to Chicago flight, settle in at a hotel close to MDW. These are some comfortable options that'll help you switch to relaxation mode:
Get exactly what you want. Booking your ride from MDW four weeks in advance often means lower prices and a wider range of vehicles.
You'll find Chicago Midway International Airport at 5700 South Cicero.

Chicago Rockford International Airport (RFD)

Chicago Rockford International Airport (RFD) is about 145 kilometres from the centre of Chicago. It'll take you about 1 hour 40 minutes to get to the city centre in a ride-share or taxi after your flight from Ontario International Airport to Chicago.
Public transport will take you there in about 2 hours.
If you don't want to make the trip to the centre, find a hotel near RFD. Make yourself comfortable at one of these options after your ONT to Chicago flight:
Rental companies sometimes offer discounts on early bookings, so reserve your ride from RFD a few weeks ahead of your flight from Ontario International Airport to Chicago. Plan ahead and your wallet will thank you.
Chicago Rockford International Airport can be found at 2 Airport Cir.

Best time to go to Chicago

It's time to pick your trip dates for your flight from Ontario International Airport to Chicago. July is the busiest month for a trip to Chicago. If you like a more low-key vibe, go in January.
Book a Ontario International Airport to Chicago plane ticket with a departure in July to explore the city during its warmest month. Expect temperatures to range from 16ºC to 28ºC.
January has average temperatures of between -12ºC and 3ºC. Search for a cheap ticket from ONT to Chicago around that time if you'd rather travel in cooler conditions.

More about Chicago

After booking your flight from Ontario International Airport to Chicago, choose a hotel that puts you where you want to be. Make one of these accommodation options your base for exploring Chicago:
There are so many things to explore in this city it can be hard to figure out where to start. Art Institute of Chicago, Millennium Park and Willis Tower are popular attractions which should be on every Chicago itinerary.

Explore more of the United States

Columbus is just one of the many places in the United States waiting to be explored once you've seen Chicago. Around 451 kilometres away to the southeast, its best attractions include Franklin Park Conservatory and Botanical Gardens, Whetstone Park / Park of Roses and Ohio Theatre.
Indianapolis is another sought-after destination in the United States and is around 257 kilometres southeast of Chicago. No trip is complete without experiencing Lucas Oil Stadium, Eiteljorg Museum and The Children's Museum of Indianapolis.