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Cheap flights from Seattle to Ontario from C$ 142

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 25/1. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — YYZ
11 Jan — 18 Jan1
1 adult
1 adult, Economy, 0 bags

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 12 December 2025.

Wed 31/128:10 a.m.SEA - YYZ
Nonstop4h 43mAir Canada
Wed 7/17:50 p.m.YYZ - SEA
Nonstop5h 26mAir Canada
Deal found 10/12C$ 348
Wed 31/125:02 a.m.SEA - YYZ
1 stop14h 39mUnited Airlines
Wed 7/17:50 p.m.YYZ - SEA
Nonstop5h 26mUnited Airlines
Deal found 10/12C$ 479
Wed 31/128:00 a.m.SEA - YYZ
Nonstop4h 35mMultiple Airlines
Mon 5/110:15 p.m.YYZ - SEA
2 stops38h 38mMultiple Airlines
Deal found 10/12C$ 512
Wed 31/128:10 a.m.SEA - YYZ
Nonstop4h 43mAir Canada
Mon 5/16:45 p.m.YYZ - SEA
1 stop17h 30mAir Canada
Deal found 10/12C$ 519
Wed 31/123:50 p.m.SEA - YYZ
2 stops14h 46mUnited Airlines
Mon 5/19:00 a.m.YYZ - SEA
1 stop12h 46mUnited Airlines
Deal found 10/12C$ 557
Sat 27/127:00 a.m.SEA - YYZ
1 stop13h 59mUnited Airlines
Tue 6/19:00 p.m.YYZ - SEA
1 stop17h 32mUnited Airlines
Deal found 10/12C$ 596
Sat 27/128:00 p.m.SEA - YYZ
1 stop6h 59mAir Canada
Tue 6/18:55 p.m.YYZ - SEA
2 stops15h 20mAir Canada
Deal found 10/12C$ 621
Mon 29/127:00 a.m.SEA - YYZ
1 stop11h 21mUnited Airlines
Mon 5/19:00 a.m.YYZ - SEA
1 stop12h 46mUnited Airlines
Deal found 9/12C$ 685
Mon 29/125:49 p.m.SEA - YTZ
1 stop22h 08mMultiple Airlines
Mon 5/19:20 a.m.YTZ - SEA
1 stop26h 25mMultiple Airlines
Deal found 9/12C$ 767
Wed 31/1210:39 p.m.SEA - YTZ
2 stops20h 24mMultiple Airlines
Mon 5/17:40 p.m.YTZ - SEA
1 stop17h 56mMultiple Airlines
Deal found 10/12C$ 819
Sat 27/1211:10 p.m.SEA - YUL
1 stop14h 17mMultiple Airlines
Sun 4/17:30 p.m.YUL - SEA
2 stops40h 24mMultiple Airlines
Deal found 11/12C$ 958
Tue 23/128:00 p.m.SEA - YUL
1 stop7h 44mAir Canada
Sat 10/11:15 p.m.YUL - SEA
2 stops11h 51mAir Canada
Deal found 11/12C$ 1,078

Find flight deals from Seattle to Ontario

Keep the following information in mind while searching for Seattle to Ontario flight deals. Data was last updated 12 December 2025.

Round-trip from

C$ 346

One-way from

C$ 142

Popular in

December

Cheapest in

November

Average price

C$ 763

Good round-trip deal

C$ 375 or less

Good one-way deal

C$ 267 or less
Air Canada
  • Air Canada
  • 17/1-20/1
  • Nonstop
  • 10h 09m total
  • Seattle to Ontario
Search Deals
Air Canada
  • Air Canada
  • 25/1
  • 1 total stop
  • 7h 15m total
  • Seattle to Ontario
Search Deals
High demand for flights, 7% potential price rise
Search Deals
Cheapest flight prices on average. 3% potential price decrease (C$ 28 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in December 2025
Search Deals
Price to beat on a round-trip flight from Seattle/Tacoma Intl to Ontario.
Search Deals
Price to beat on a one-way 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 12 December 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

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Fri 30/1

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Sun 1/2

4:45 p.m.-7:17 p.m.

Nonstop5h 32m

C$ 350

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Thu 12/2

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Sat 7/3

4:45 p.m.-7:18 p.m.

Nonstop5h 33m

C$ 361

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Thu 5/3

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Mon 9/3

4:45 p.m.-7:18 p.m.

Nonstop5h 33m

C$ 376

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Fri 6/3

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Mon 9/3

4:45 p.m.-7:18 p.m.

Nonstop5h 33m

C$ 376

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Thu 12/3

7:55 a.m.-3:35 p.m.

Nonstop4h 40m

Toronto Pearson Intl

Sun 15/3

4:45 p.m.-7:18 p.m.

Nonstop5h 33m

C$ 376

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sat 24/1

6:48 a.m.-10:37 p.m.

1 stop12h 49m

Toronto Pearson Intl

Sat 31/1

9:00 a.m.-6:14 p.m.

1 stop12h 14m

C$ 381

SeattleOttawa

SEA - YOW

SEAYOW

Seattle/Tacoma Intl

Mon 26/1

3:10 p.m.-4:53 p.m.

1 stop22h 43m

Ottawa

Mon 2/2

5:40 a.m.-2:19 p.m.

2 stops11h 39m

C$ 383

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Tue 20/1

5:00 a.m.-3:02 p.m.

1 stop7h 02m

Toronto Pearson Intl

Tue 27/1

2:57 p.m.-11:15 p.m.

1 stop11h 18m

C$ 388

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Thu 22/1

8:00 p.m.-8:46 a.m.

2 stops9h 46m

London

Mon 26/1

5:40 p.m.-10:16 p.m.

1 stop7h 36m

C$ 390

SeattleHamilton

SEA - YHM

SEAYHM

Seattle/Tacoma Intl

Sun 25/1

3:10 p.m.-5:17 p.m.

1 stop23h 07m

Hamilton

Sun 1/2

6:10 p.m.-2:19 p.m.

1 stop23h 09m

C$ 394

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/12

Showing 1-10 of 60 results
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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

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

Currently, March is the cheapest month in which you can book a flight from Seattle to Region of Ontario (average of C$ 167). Flying from Seattle to Region of Ontario in December is currently the most expensive (average of C$ 360). 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 ON?

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 12 December 2025.

When flying from Seattle to Region of Ontario, the time of day you fly usually plays a role in the price. Save by searching for a flight in the evening, which can drop the price by up to 18% versus a flight in the morning.

Weekly flight availability from Seattle to Region of Ontario

Explore weekly flight availability from Seattle to Ontario. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated 12 December 2025.

The most flights from SEA to CAON are scheduled on a Tuesday (6 on average). You will have fewer flight options on Monday, which is when the least amount of flights are scheduled (4 on average).

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 12 December 2025.
Check out reviews from past customers who have flown with Alaska Airlines,United Airlines, andWestJet from Seattle to Ontario to help guide your decision. Users have also rated airlines in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
11,432 reviews
Check prices

Entertainment

7.0

Food

7.1

Boarding

8.1

Comfort

7.8

Crew

8.5

Overall

8.0

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
11,432 reviews
Alaska Airlines
8.0
Very good
11,432 reviews
Check prices

Entertainment

7.0

Food

7.1

Boarding

8.1

Comfort

7.8

Crew

8.5

Overall

8.0

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.
United Airlines
7.4
Good
9,095 reviews
Alaska Airlines
8.0
Very good
11,432 reviews
Check prices

Entertainment

7.0

Food

7.1

Boarding

8.1

Comfort

7.8

Crew

8.5

Overall

8.0

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.
WestJet
7.2
Good
3,195 reviews
Alaska Airlines
8.0
Very good
11,432 reviews
Check prices

Entertainment

7.0

Food

7.1

Boarding

8.1

Comfort

7.8

Crew

8.5

Overall

8.0

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.
Air Canada
7.1
Good
10,517 reviews
Alaska Airlines
8.0
Very good
11,432 reviews
Check prices

Entertainment

7.0

Food

7.1

Boarding

8.1

Comfort

7.8

Crew

8.5

Overall

8.0

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 airport do you fly from for flights from Seattle to Ontario?

    Located just 18.4 km from the city centre, Seattle/Tacoma Intl (SEA) is the airport most travellers will use when flying to Ontario from Seattle.

  • How long is the flight from Seattle to Region of Ontario?

    There are many flights that can get you from Seattle to Region of Ontario in 4h 40m. Fly via Alaska Airlines, WestJet, or Air Canada to get the fastest option. Airlines will cover a distance of 3306 km. Both multi-stop and direct flights can be found to your destination and back.

  • What are the cheapest airlines to fly from Seattle to Region of Ontario one-way?

    The cheapest airlines for a one-way flight from Seattle to Region of Ontario are WestJet (C$ 139), Alaska Airlines (C$ 153), and Air Canada (C$ 162).

  • What are the most popular routes from Seattle to Region of Ontario?

    When deciding which route to take from Seattle to Region of Ontario consider Seattle/Tacoma Intl - Toronto Pearson Intl, Seattle/Tacoma Intl - Montreal Pierre Elliott Trudeau Intl or Seattle/Tacoma Intl - Toronto Island as they are the most popular.

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

    Consider Alaska Airlines (96%), Qatar Airways (96%) or Hawaiian Airlines (94%) when booking your flight. These represent the most reliable airlines when flying from Seattle to Region of Ontario.

  • What are the cheapest flights from Seattle to Region of Ontario?

    The cheapest flight price from Seattle to Region of Ontario is C$ 137. On average you can expect to pay C$ 654. The most popular route, (Seattle/Tacoma Intl - Toronto Pearson Intl), can usually be booked for C$ 299.

  • 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 Region of Ontario?

    Currently, March is the cheapest month in which you can book a flight from Seattle to Region of Ontario (average of C$ 167). Flying from Seattle to Region of Ontario in December is currently the most expensive (average of C$ 360). 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

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Alternative routes for Seattle to Ontario

See prices for flight routes from nearby airports that may be better suited for you.
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Top 4 airlines flying from Seattle to Ontario

Discover the top 4 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 12 December 2025.
AirlineCheapestAverageFlexibilityOn-time
WestJetCheapestC$ 285AverageC$ 389FlexibilityNo cancel feeOn-time60%
Search WestJet flights
Air CanadaCheapestC$ 364AverageC$ 461FlexibilityNo cancel feeOn-time67%
Search Air Canada flights
Alaska AirlinesCheapestC$ 375AverageC$ 783FlexibilityNo cancel feeOn-time75%
Search Alaska Airlines flights
United AirlinesCheapestC$ 487AverageC$ 538FlexibilityNo cancel feeOn-time69%
Search United 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?

Cheapflights goes through 900+ travel sites to look for the best flight deals for flights from Seattle to Ontario. Too many options? Cheapflights also provides filters for things like airlines, price ranges, and number of stops to help you make a decision easily.

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

Cheapflights simply makes it quick and affordable to book flights from Seattle to Ontario by bringing together all flight options from hundreds of airlines and agencies online — and put it in one place for you to choose from. Plus, Cheapflights is 100% free to use for all.

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

Users can book flights with no change fees policies with our dedicated filters. Book flights from Seattle to Ontario flexibly with Cheapflights today.

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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