Find flights
Deals
When to book
Airlines
FAQs

Cheap flights from Seattle to Ontario from C$ 125

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 24/1. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — ONT
26 Nov — 3 Dec1
1 adult
1 adult, Economy, 0 bags

Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Ontario are usually found in March or January, booked 51 days in advance, depart on a Saturday or Tuesday and return on a Friday

Find 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 27 October 2025.

Sat 15/1112:58 p.m.SEA - ONT
1 stop10h 52mFrontier
Mon 17/116:53 a.m.ONT - SEA
1 stop29h 14mFrontier
Deal found 25/10C$ 182
Mon 15/1211:01 a.m.SEA - ONT
1 stop10h 16mFrontier
Thu 15/16:30 a.m.ONT - SEA
2 stops9h 58mFrontier
Deal found 27/10C$ 228
Sat 15/118:05 p.m.SEA - ONT
Nonstop2h 50mDelta
Tue 18/1111:48 a.m.ONT - SEA
Nonstop2h 57mDelta
Deal found 25/10C$ 248
Sat 15/118:22 a.m.SEA - ONT
Nonstop2h 43mHawaiian Airlines
Mon 17/116:11 p.m.ONT - SEA
Nonstop2h 49mHawaiian Airlines
Deal found 25/10C$ 257
Sat 15/116:15 p.m.SEA - ONT
Nonstop2h 38mAlaska Airlines
Sun 16/116:00 a.m.ONT - SEA
Nonstop2h 50mAlaska Airlines
Deal found 24/10C$ 262
Mon 15/1211:01 a.m.SEA - ONT
1 stop10h 16mMultiple Airlines
Thu 15/16:00 a.m.ONT - SEA
Nonstop2h 54mMultiple Airlines
Deal found 27/10C$ 270
Sat 13/128:43 a.m.SEA - ONT
Nonstop2h 36mAlaska Airlines
Sun 21/127:19 p.m.ONT - SEA
Nonstop2h 51mAlaska Airlines
Deal found 27/10C$ 276
Sat 15/1111:35 a.m.SEA - ONT
1 stop5h 30mAlaska Airlines
Tue 18/1111:59 a.m.ONT - SEA
Nonstop2h 51mAlaska Airlines
Deal found 25/10C$ 281
Sat 15/1111:35 a.m.SEA - ONT
1 stop5h 30mAlaska Airlines
Mon 17/116:03 p.m.ONT - SEA
1 stop5h 29mAlaska Airlines
Deal found 25/10C$ 288
Wed 3/125:15 a.m.SEA - ONT
1 stop6h 45mSouthwest
Sun 7/129:50 a.m.ONT - SEA
1 stop7h 30mSouthwest
Deal found 26/10C$ 290
Sat 6/123:57 p.m.SEA - ONT
Nonstop2h 36mAlaska Airlines
Sun 7/127:10 a.m.ONT - SEA
1 stop4h 39mAlaska Airlines
Deal found 25/10C$ 295

Cheap 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 27 October 2025.

Round-trip from

C$ 182

One-way from

C$ 125

Popular in

December

Cheapest in

March

Average price

C$ 290

Good round-trip deal

C$ 168 or less
Frontier
  • Frontier
  • 15/11-17/11
  • 2 total stops
  • 40h 06m total
  • Seattle to Ontario
Search Deals
United Airlines
  • United Airlines
  • 24/11
  • 1 total stop
  • 5h 31m total
  • Seattle to Ontario
Search Deals
Highest demand for flights based on searches. 6% potential increase in price (C$ 27 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease (C$ 10 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in October 2025
Search Deals
Price to beat on a round-trip flight from Seattle/Tacoma Intl to Ontario.
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 27 October 2025.
Use the filters below to find and compare flights from Seattle to Ontario that are best for you.

Fly from

Seattle

Fly to

Ontario

Route

Depart

Return

Price

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 6/12

5:00 a.m.-12:32 p.m.

1 stop7h 32m

Ontario

Mon 15/12

1:34 p.m.-9:46 p.m.

1 stop8h 12m

C$ 248

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 13/12

8:05 p.m.-10:47 p.m.

Nonstop2h 42m

Ontario

Mon 15/12

6:40 a.m.-9:45 a.m.

Nonstop3h 05m

C$ 262

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Fri 6/3

8:05 p.m.-10:37 p.m.

Nonstop2h 32m

Ontario

Sun 8/3

6:00 a.m.-8:50 a.m.

Nonstop2h 50m

C$ 276

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 13/12

3:57 p.m.-6:33 p.m.

Nonstop2h 36m

Ontario

Sun 21/12

7:19 p.m.-10:10 p.m.

Nonstop2h 51m

C$ 276

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Fri 5/12

8:30 a.m.-11:13 a.m.

Nonstop2h 43m

Ontario

Mon 8/12

12:40 p.m.-3:37 p.m.

Nonstop2h 57m

C$ 276

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Mon 15/12

8:55 p.m.-11:29 p.m.

Nonstop2h 34m

Ontario

Thu 15/1

11:53 a.m.-2:44 p.m.

Nonstop2h 51m

C$ 276

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Fri 6/2

7:45 p.m.-10:29 p.m.

Nonstop2h 44m

Ontario

Sun 8/2

7:30 a.m.-10:36 a.m.

Nonstop3h 06m

C$ 276

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Thu 5/3

3:45 p.m.-6:17 p.m.

Nonstop2h 32m

Ontario

Mon 9/3

6:00 a.m.-8:50 a.m.

Nonstop2h 50m

C$ 276

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Sat 24/1

3:35 p.m.-8:15 p.m.

1 stop4h 40m

Ontario

Sat 31/1

7:00 a.m.-11:33 a.m.

1 stop4h 33m

C$ 276

SeattleOntario

SEA - ONT

SEAONT

Seattle/Tacoma Intl

Thu 25/12

9:35 p.m.-12:14 a.m.

Nonstop2h 39m

Ontario

Sat 10/1

4:03 p.m.-6:54 p.m.

Nonstop2h 51m

C$ 276

Flights are sorted by cheapest round-trip flights first.

Deals found on 25/10

Showing 1-10 of 22 results
1
2
3

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?

Use this chart to determine the optimal time to book a round-trip flight from Seattle to Ontario. Price data was last updated on 24 October 2025.

Booking 51 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, January is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 53). Flying from Seattle to Ontario in July is currently the most expensive (average of C$ 167). 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 27 October 2025.

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 morning could potentially save you up to 37% on airfare.

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 27 October 2025.
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
8.0
Very good
11,194 reviews
Check prices

Boarding

8.1

Crew

8.5

Overall

8.0

Food

7.1

Entertainment

7.0

Comfort

7.8

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Alaska Airlines
8.0
Very good
11,194 reviews
Alaska Airlines
8.0
Very good
11,194 reviews
Check prices

Boarding

8.1

Crew

8.5

Overall

8.0

Food

7.1

Entertainment

7.0

Comfort

7.8

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.
Frontier
5.8
Fair
3,123 reviews
Alaska Airlines
8.0
Very good
11,194 reviews
Check prices

Boarding

8.1

Crew

8.5

Overall

8.0

Food

7.1

Entertainment

7.0

Comfort

7.8

Reviews

1 / 20
8.0
Excellent

Anonymous,Sep 2025

SEA - MKE

The crew were excellent, flight good, but the actual space for a person to occupy for 4 hours seems to get smaller and smaller 🤣. I am not overweight, and average height….very uncomfortable,, especially when I couldn’t recliner the seat at all, and the pocket in front doesn’t accommodate a water bottle.

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 38m on average. When it comes time to book airfare, you have a few options: there are 12 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, 15 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$ 276, United Airlines can have you in Ontario from Seattle in 2h 32m. 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$ 95. Another airline that can offer you cheap pricing is Alaska Airlines. Frontier is currently priced 69% 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: Delta (96%), SkyWest Airlines (95%), WestJet (92%).

  • What are the cheapest flights from Seattle to Ontario?

    Looking for the cheapest flight from Seattle to Ontario? While on average our users pay C$ 310, our data indicates the cheapest price to be C$ 166. The most popular route (Seattle/Tacoma Intl - Ontario), is priced around C$ 257.

  • 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, January is the cheapest month in which you can book a flight from Seattle to Ontario (average of C$ 53). Flying from Seattle to Ontario in July is currently the most expensive (average of C$ 167). 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

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Seattle to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
Seattle to Los Angeles flights
Seattle to Las Vegas flights
Seattle to San Francisco flights
Seattle to Palm Springs flights
Seattle to San Diego flights
Seattle to San Jose flights
Seattle to Reno flights
Bellingham to Santa Ana flights
Spokane to San Francisco flights
Portland to Los Angeles flights
Bellingham to Los Angeles flights
Seattle to Oakland flights
Bellingham to Oakland flights
Bellingham to Burbank flights
Bellingham to Palm Springs flights
Bellingham to San Francisco flights
Spokane to Los Angeles flights
Seattle to Sacramento flights
Seattle to Santa Ana flights
Seattle to Burbank flights
Spokane to Las Vegas flights
Bellingham to Sacramento flights
Bellingham to San Diego flights
Bellingham to Las Vegas flights
Portland to San Francisco flights
Bellingham to Reno flights

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 27 October 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapestC$ 95AverageC$ 262FlexibilityNo cancel feeOn-time62%
Search Frontier flights
Alaska AirlinesCheapestC$ 219AverageC$ 310FlexibilityNo 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!

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.