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Cheap flights from Seattle to Ontario from C$ 153

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 8/12. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ONT
11 Jul — 18 Jul1
1 adult
1 adult, Economy, 0 bags
Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Ontario are usually found in October or September, booked 60 days in advance, depart on a Friday or Tuesday and return on a Tuesday

Cheap flight deals from Seattle to Ontario

Enter your travel dates to find the best prices.

Cheapest flights from Seattle to Ontario
Explore the most affordable flight options available from Seattle to Ontario. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 11 June 2026.

Wed 19/811:53 a.m.
SEA
-
ONT
Nonstop2h 46m
Frontier
Tue 25/84:04 p.m.
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 11/6C$ 249
Thu 20/811:53 a.m.
SEA
-
ONT
Nonstop2h 46m
Frontier
Tue 25/84:04 p.m.
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 11/6C$ 263
Mon 24/811:53 a.m.
SEA
-
ONT
Nonstop2h 46m
Frontier
Fri 28/84:04 p.m.
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 8/6C$ 287
Mon 31/811:53 a.m.
SEA
-
ONT
Nonstop2h 46m
Frontier
Sun 6/94:04 p.m.
ONT
-
SEA
Nonstop2h 54m
Frontier
Deal found 10/6C$ 291
Fri 4/911:53 a.m.
SEA
-
ONT
Nonstop2h 46m
Frontier
Tue 8/96:00 a.m.
ONT
-
SEA
1 stop8h 04m
Frontier
Deal found 6/6C$ 298
Wed 23/94:10 p.m.
SEA
-
ONT
1 stop4h 45m
Southwest
Sat 26/95:40 a.m.
ONT
-
SEA
1 stop7h 15m
Southwest
Deal found 9/6C$ 311
Sat 29/86:00 a.m.
SEA
-
ONT
1 stop6h 20m
Southwest
Sat 5/92:55 p.m.
ONT
-
SEA
1 stop8h 00m
Southwest
Deal found 9/6C$ 312
Wed 5/85:55 a.m.
SEA
-
ONT
1 stop4h 20m
Southwest
Wed 5/84:45 p.m.
ONT
-
SEA
1 stop6h 40m
Southwest
Deal found 9/6C$ 318
Wed 1/77:41 p.m.
SEA
-
ONT
1 stop14h 24m
Frontier
Wed 8/73:40 p.m.
ONT
-
SEA
1 stop18h 59m
Frontier
Deal found 9/6C$ 322
Sat 22/83:30 p.m.
SEA
-
ONT
1 stop4h 31m
United Airlines
Sat 29/811:00 a.m.
ONT
-
SEA
1 stop7h 29m
United Airlines
Deal found 9/6C$ 323

Find flight deals from Seattle to Ontario

Discover tips and strategies to find the most affordable flight options for your journey from Seattle (SEA) to Ontario (ONT). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated 11 June 2026.

Round-trip from

C$ 287

One-way from

C$ 159

Popular in

February

Cheapest in

October

Average price

C$ 347
Frontier
  • Frontier
  • 24/8-28/8
  • Nonstop
  • 5h 40m total
  • Seattle to Ontario
Search Deals
Southwest
  • Southwest
  • 23/9
  • 1 total stop
  • 6h 15m total
  • Seattle to Ontario
Search Deals
Highest demand for flights based on searches. 12% potential increase in price (C$ 72 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease (C$ 20 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in June 2026
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Seattle to Ontario 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 629,999 searches. Data last updated 11 June 2026.
Use the filters below to find and compare flights from Seattle to Ontario that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 22/9

10:37 a.m.-3:47 p.m.

1 stop5h 10m

Ontario

Sat 26/9

7:12 a.m.-1:38 p.m.

1 stop6h 26m

C$ 358

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Thu 20/8

10:00 a.m.-4:10 p.m.

1 stop6h 10m

Ontario

Tue 25/8

7:12 a.m.-12:50 p.m.

1 stop5h 38m

C$ 372

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Thu 19/11

7:55 p.m.-10:43 p.m.

Nonstop2h 48m

Ontario

Mon 23/11

5:05 p.m.-10:05 p.m.

1 stop5h 00m

C$ 428
Quickest round-trip

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Fri 31/7

8:25 a.m.-11:17 a.m.

Nonstop2h 52m

Ontario

Mon 3/8

11:56 a.m.-2:50 p.m.

Nonstop2h 54m

C$ 456

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Mon 31/8

3:30 p.m.-8:01 p.m.

1 stop4h 31m

Ontario

Sun 6/9

1:56 p.m.-6:32 p.m.

1 stop4h 36m

C$ 463

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 14/7

7:30 a.m.-2:05 p.m.

2 stops6h 35m

Ontario

Fri 17/7

7:30 p.m.-11:35 p.m.

1 stop4h 05m

C$ 485

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 28/7

5:40 a.m.-9:35 a.m.

1 stop3h 55m

Ontario

Sat 1/8

4:55 p.m.-1:15 a.m.

2 stops8h 20m

C$ 491

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 31/10

12:13 p.m.-4:50 p.m.

1 stop4h 37m

Ontario

Mon 9/11

7:15 a.m.-2:50 p.m.

2 stops7h 35m

C$ 532

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Mon 6/7

5:00 a.m.-10:30 a.m.

1 stop5h 30m

Ontario

Wed 22/7

4:35 p.m.-11:35 p.m.

2 stops7h 00m

C$ 532

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Tue 7/7

5:35 p.m.-10:10 p.m.

1 stop4h 35m

Ontario

Tue 14/7

4:35 p.m.-11:35 p.m.

2 stops7h 00m

C$ 567

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/6

Showing 1-10 of 23 resultsSorted by cheapest first
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Best time to book a flight from Seattle to Ontario

Have a flexible travel schedule? Discover the best time to fly to Ontario from Seattle 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 Seattle to Ontario

How far ahead should I book a flight from Seattle to Ontario?

Booking 59 days in advance of your planned departure date is, on average, the best time to get cheap flights from Seattle to Ontario. The general trend is that the closer you book to the departure date, the more expensive your flight will be.

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

Currently, October is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 261). Flying from Seattle to Ontario in February is currently the most expensive (average of C$ 525). 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 SEA to ONT?

Find hourly flight availability from Seattle to Ontario. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated 11 June 2026.

One of the essential ways to save on airfare from Seattle to Ontario is to remain as flexible as possible. Flights that are at noon tend to be the most expensive. A flight in the afternoon could potentially save you up to 44% on airfare.

How much does it cost to fly round-trip from Seattle to Ontario?

Reviews of airlines servicing Ontario

Get insights into the airlines that provide service to Ontario. 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 Ontario. Reviews last updated 11 June 2026.
Read reviews from past customers who have flown Alaska Airlines and Frontier from Seattle to Ontario. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
7.9
Good
12,479 reviews
Check prices

Food

7.0

Boarding

8.1

Overall

7.9

Entertainment

7.0

Crew

8.5

Comfort

7.8

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2026

SEA - RNO

There was a delay and my husband needs a wheelchair and we were moved from 1 gate to another.
Alaska Airlines
7.9
Good
12,479 reviews
Alaska Airlines
7.9
Good
12,479 reviews
Check prices

Food

7.0

Boarding

8.1

Overall

7.9

Entertainment

7.0

Crew

8.5

Comfort

7.8

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2026

SEA - RNO

There was a delay and my husband needs a wheelchair and we were moved from 1 gate to another.
Frontier
5.6
Fair
2,898 reviews
Alaska Airlines
7.9
Good
12,479 reviews
Check prices

Food

7.0

Boarding

8.1

Overall

7.9

Entertainment

7.0

Crew

8.5

Comfort

7.8

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2026

SEA - RNO

There was a delay and my husband needs a wheelchair and we were moved from 1 gate to another.

Related info for your journey

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

  • What airports do I use to fly from Seattle to Ontario?

    To fly from Seattle to Ontario, you need to book a flight from Seattle/Tacoma Intl (SEA) to Ontario (ONT). Nonstop flights to Ontario from Seattle/Tacoma Intl take 2h 44m on average. When it comes time to book airfare, you have a few options: there are 13 outbound flights from Seattle/Tacoma Intl to Ontario offered by 2 different airlines.

  • How popular is this Seattle to Ontario flight route?

    Within the past month, 19 users have taken a look at flights from Seattle/Tacoma Intl to Ontario.

  • How long is the flight from Seattle to Ontario?

    For as low as C$ 428, Alaska Airlines can have you in Ontario from Seattle in 2h 48m. Seattle and Ontario are separated by a distance of 1539 km. This flight may include one or multiple stops.

  • What are the cheapest airlines flying from Seattle to Ontario round-trip?

    Cheapflights users have booked flights from Seattle to Ontario round-trip from C$ 238. Another airline that can offer you cheap pricing is Alaska Airlines. Frontier is currently priced 36% below the average price you’ll pay for this route.

  • What are the most reliable airlines from Seattle to Ontario?

    Looking for the most reliable airlines to get you to your destination on time? Our data shows these are most likely to get you from Seattle to Ontario on time: Frontier (100%), Volaris (100%), SkyWest Airlines (92%).

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

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

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

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

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

    Yes. Cheapflights offers flight deals from Seattle to Ontario 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 Seattle to Ontario?

    Currently, October is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 261). Flying from Seattle to Ontario in February is currently the most expensive (average of C$ 525). 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.

See more FAQs

Browse thousands of different options on Cheapflights for your next trip

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Top 2 airlines flying from Seattle to Ontario

Discover the top 2 airlines that operate flights from Seattle to Ontario. 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 629,999 searches. Data last updated 11 June 2026.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapestC$ 238AverageC$ 340FlexibilityNo cancel feeOn-time62%
Search Frontier flights
Alaska AirlinesCheapestC$ 323AverageC$ 442FlexibilityNo cancel feeOn-time75%
Search Alaska Airlines flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Seattle to Ontario?

When you search for this flight from Seattle to Ontario, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

Why should you use Cheapflights to find cheap flight tickets from Seattle to Ontario?

It’s simple! Cheapflights, which is free to use for everyone, saves millions of users time and money every year by helping them find the cheapest and most suitable flights from Seattle to Ontario.

Can Cheapflights find flights from Seattle to Ontario with no change fees?

Yes! Cheapflights helps users easily find flights from Seattle to Ontario with no change fees.

Can Cheapflights notify me if prices for flights from Seattle to Ontario become cheaper?

Yes, and it’s super simple to set up. Click the bell icon next to the flight deals above and provide a valid email address to enable Price Alerts. That’s it!

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