$156 Cheap United flights from St. Louis to Ontario (STL to ONT)

Find The Best Day To Fly from St. Louis to Ontario

Amazing United STL to ONT Flight Deals

The cheapest flights to Los Angeles - Ontario Intl. found within the past 7 days were $320 round trip and $156 one way. Prices and availability subject to change. Additional terms may apply.

Mon, Aug 11 - Tue, Aug 12
STL
St. Louis
ONT
Ontario
$320 Roundtrip, found 1 day ago
$320
Roundtrip
found 1 day ago
Select United flight, departing Mon, Aug 11 from St. Louis to Ontario, returning Tue, Aug 12, priced at $320 found 1 day ago

ONT From STL Economy Coach Packages on Similar Airlines

Price found within the past 48 hours. Click for updated prices.
La Quinta Inn & Suites by Wyndham Moreno Valley

La Quinta Inn & Suites by Wyndham Moreno Valley

2.5 out of 5
per person
Jul 23 - Jul 28
found 8 hours ago
Roundtrip non-stop flight included
St. Louis (STL) to Ontario (ONT)
Dynasty Suites Redlands

Dynasty Suites Redlands

3 out of 5
per person
Jul 23 - Jul 28
found 8 hours ago
Roundtrip non-stop flight included
St. Louis (STL) to Ontario (ONT)
La Quinta Inn & Suites by Wyndham Ontario Airport

La Quinta Inn & Suites by Wyndham Ontario Airport

3 out of 5
per person
Jul 23 - Jul 28
found 8 hours ago
Roundtrip non-stop flight included
St. Louis (STL) to Ontario (ONT)
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Frequently asked questions

Can I catch a flight from Lambert-St. Louis Intl. Airport (STL) to ONT right now?
It’s always prudent to know about any quarantine requirements and travel advice reports in place in your destination city. Make sure you check out our Covid-19 Travel Advisor for up-to-date information on booking a flight to Ontario Airport.
What terminal is United Airlines at St. Louis Lambert International Airport?
If you’re flying with United Airlines from Lambert-St. Louis Intl. Airport (STL) to ONT, you should be able to find out the terminal information once you’re issued with your ticket. If not, get in touch with your airline.
Are there United Airlines non-stop flights from STL to ONT?
As you can’t fly nonstop from STL to ONT with United Airlines, make the most of your stopover. Treat yourself to a couple of refreshments at a comfortable airport bar, or wander about the terminal and indulge in some retail therapy.
How long is a United Airlines flight from STL to ONT?
Air traffic and weather permitting, your United Airlines flight from St. Louis Lambert International Airport to Los Angeles - Ontario Intl. Airport (ONT) should take approximately 5 hours and 1 minute. You’ll have plenty of time to enjoy a drink or two, get some shut-eye and revise your itinerary before you touch down.
How many direct and indirect flights does United Airlines fly from STL to ONT?
You’ll have loads of choice if you’d prefer to fly with United Airlines between STL and ONT. Currently, it has about 2 flights every day.
If I am not able to travel due to COVID-19, can I change my booking to a later date?
For more info about changing your flight to Los Angeles - Ontario Intl. Airport (ONT), please visit our Customer Service Portal.
What is the best day to buy a plane ticket?
This just in! Airfares offered on Thursdays tend to be the cheapest, according to flight demand on Travelocity in 2021. Tuesday and Wednesday prices are also good, but you may want to prepare your budget if booking during the weekend, as data shows that is when prices are generally at their highest.
What are the cheapest days to fly?
Frequent travelers may already know this, but earlier in the week can be the cheapest time to fly. In 2021, flights departing on a Monday were generally the cheapest of the week, whereas you may pay a premium for weekend flights when demand is usually high. On average, tickets were most expensive for Saturday departures, so if you need to fly out on a weekend, you might look for deals ahead of time.
How far in advance can you book a flight?
Trying to figure out how early you should book your flight? It’s possible to start comparing international airfares on Travelocity up to 12 months in advance. However, it does depend on the carrier as not all airlines release their prices that far out. According to our 2021 flight demand trends, last minute planners can still bag a bargain with some of the cheapest fares appearing 0-2 weeks prior to their travel dates.*According to flight demand on Travelocity.com from January to December 2021. Savings are subject to change based on departure location, date and destination.

Discover our best United flight from St. Louis STL to Ontario ONT 

To find the best deals on flights to St. Louis from Ontario with United, just enter your travel dates, filter by United, and hit search. You’ll find flights to choose from and can sort by price, flight duration, and arrival or departure time.  

 

Return flights from St. Louis STL to Ontario ONT with United 

If you’re planning a round trip, booking return flights with United is usually the most cost-effective option. With airfares ranging from $320 to $320, it’s easy to find a flight that suits your budget. Prices and availability subject to change. Additional terms may apply. 

 

Book one-way United flights from St. Louis STL to Ontario ONT 

A one-way ticket gives you much greater flexibility—allowing you to choose your return date, destination, and time whenever you’re ready. By booking in advance you can find great deals on one-way tickets too. Right now, a one-way United flight from St. Louis to Ontario costs from $156. Prices and availability subject to change. Additional terms may apply. 

 

The easy way to find cheap flights to Ontario ONT from  St. Louis STL with United 

To find a cheap United flight from St. Louis STL to Ontario ONT, sort your search results by price or filter by budget. Thanks to Travelocity’s Price Match Promise, if you find a better airfare deal anywhere else within 24 hours, we’ll credit or refund the difference. 

 

How to find our best airfare deals on United flights from St. Louis STL to Ontario ONT 

If you’re looking for cheap flights, it helps to be flexible when it comes to your travel dates. You’ll usually find lower cost tickets when you travel during quieter months such as August, or if you book a flight with a stopover. 

 

Find nonstop flights from St. Louis STL to Ontario ONT with United 

If you’re keen to be on Ontario soil fast, don’t waste time with a stopover—filter your search results to show direct United flights only. The journey takes around hour(s) min(s) – so you’ll be there before you know it. 

 

Flexible airline tickets for United flights from St. Louis STL to Ontario ONT 

Make sure you’re not out of pocket if plans change by choosing a flexible ticket with penalty-free amendment and cancellation options. Use our ‘no change fee’ filter to see which flights have this option.  

 

There are a lot of reasons to book your flights to Ontario ONT from  St. Louis STL with United on Travelocity 

At Travelocity our vast and up-to-the-minute inventory puts all of our best flight deals in one place. So, whether you’re traveling on business or jetting off with friends and family, you can trust Travelocity to get you there.

United Airports
Hop on a(n) United flight today by flying to many destinations out of these domestic and international airports:
Airport code
Country
Airport name
Number of flights
ORDUSAO'Hare Intl.227
DENUSADenver Intl.226
IAHUSAGeorge Bush Intercontinental136
IADUSAWashington Dulles Intl.100
SFOUSASan Francisco Intl.64
LAXUSALos Angeles Intl.23
EWRUSALiberty Intl.20
FRADEUFrankfurt Intl.19
NRTJPNNarita Intl.19
PEKCHNCapital Intl.16

Travelers ❤️ these 🏨 after their flight to Ontario

Ontario Airport Inn
Ontario Airport Inn
2.5 out of 5
1801 E G St, Ontario, CA
This hotel doesn't skimp on freebies - guests receive free buffet breakfast, free self parking, and a free airport shuttle. Traveling on business? Take advantage ...
8.6/10 Excellent! (1,465 reviews)
Hidden gem
"This place is a hidden gem. Reminds me of an old school resort. Relaxing tropical like environment. The breakfast included was one of the best I’ve had, and their coffee, amazing. We will definitely stay here again."

Reviewed on May 3, 2025

Ontario Airport Inn
Comfort Inn & Suites near Ontario Airport
Comfort Inn & Suites near Ontario Airport
2.5 out of 5
3333 Shelby St, Ontario, CA
This hotel features an outdoor pool and a hot tub. Traveling on business? Take advantage of the business center and free WiFi in public areas. Guests will appreciate ...
8/10 Very Good! (1,141 reviews)
"Very spacious room great location by Ontario Mills and close to the airport! I will definitely be back!!"

Reviewed on May 5, 2025

Comfort Inn & Suites near Ontario Airport
Motel 6 Ontario, CA - Convention Center - Airport
Motel 6 Ontario, CA - Convention Center - Airport
2 out of 5
231 N Vineyard Ave, Ontario, CA
An outdoor pool, free self parking, and laundry facilities are featured at this motel. A snack bar/deli is provided and the front desk is staffed ...
7/10 Good! (1,008 reviews)
"The room was nice and everything was okay."

Reviewed on May 5, 2025

Motel 6 Ontario, CA - Convention Center - Airport
Lowest nightly price found within the past 24 hours based on a 1 night stay for 2 adults. Prices and availability subject to change. Additional terms may apply.
*Price based on the lowest price found within past 24 hours and based upon one night stay for two adults over the next thirty days. Prices and availability subject to change. Additional terms may apply.