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$103+ Cheap flights from Seattle (SEA) to Ontario

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 1/25. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — YYZ
Jan 11 — Jan 181
Sun 1/11
Sun 1/18
1 adult, Economy
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Cheap flight deals from Seattle to Ontario

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 December 12, 2025.

This Air Canada deal was found by Cheapflights users on 12/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/318:10 amSEA - YYZ
Nonstop4h 43mAir Canada
Wed 1/77:50 pmYYZ - SEA
Nonstop5h 26mAir Canada
Deal found 12/10$252
This United Airlines deal was found by Cheapflights users on 12/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/315:02 amSEA - YYZ
1 stop14h 39mUnited Airlines
Wed 1/77:50 pmYYZ - SEA
Nonstop5h 26mUnited Airlines
Deal found 12/10$347
This Kiwi.com deal was found by Cheapflights users on 12/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/318:00 amSEA - YYZ
Nonstop4h 35mMultiple Airlines
Mon 1/510:15 pmYYZ - SEA
2 stops38h 38mMultiple Airlines
Deal found 12/10$371
This Air Canada deal was found by Cheapflights users on 12/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/318:10 amSEA - YYZ
Nonstop4h 43mAir Canada
Mon 1/56:45 pmYYZ - SEA
1 stop17h 30mAir Canada
Deal found 12/10$376
This United Airlines deal was found by Cheapflights users on 12/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/313:50 pmSEA - YYZ
2 stops14h 46mUnited Airlines
Mon 1/59:00 amYYZ - SEA
1 stop12h 46mUnited Airlines
Deal found 12/10$404
This United Airlines deal was found by Cheapflights users on 12/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/277:00 amSEA - YYZ
1 stop13h 59mUnited Airlines
Tue 1/69:00 pmYYZ - SEA
1 stop17h 32mUnited Airlines
Deal found 12/10$432
This Air Canada deal was found by Cheapflights users on 12/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/278:00 pmSEA - YYZ
1 stop6h 59mAir Canada
Tue 1/68:55 pmYYZ - SEA
2 stops15h 20mAir Canada
Deal found 12/10$450
This United Airlines deal was found by Cheapflights users on 12/9. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/297:00 amSEA - YYZ
1 stop11h 21mUnited Airlines
Mon 1/59:00 amYYZ - SEA
1 stop12h 46mUnited Airlines
Deal found 12/9$497
This Kiwi.com deal was found by Cheapflights users on 12/9. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/295:49 pmSEA - YTZ
1 stop22h 08mMultiple Airlines
Mon 1/59:20 amYTZ - SEA
1 stop26h 25mMultiple Airlines
Deal found 12/9$556
This Kiwi.com deal was found by Cheapflights users on 12/10. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/3110:39 pmSEA - YTZ
2 stops20h 24mMultiple Airlines
Mon 1/57:40 pmYTZ - SEA
1 stop17h 56mMultiple Airlines
Deal found 12/10$594
This Air Canada deal was found by Cheapflights users on 12/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/238:00 pmSEA - YUL
1 stop7h 44mAir Canada
Sat 1/101:15 pmYUL - SEA
2 stops11h 51mAir Canada
Deal found 12/11$782
This Air Canada deal was found by Cheapflights users on 12/11. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/265:50 amSEA - YUL
1 stop8h 10mAir Canada
Fri 1/27:30 amYUL - SEA
1 stop17h 36mAir Canada
Deal found 12/11$792

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 December 12, 2025.

Most accurate provider

Mytrip
3 stars

Most trusted provider

Mytrip
3 stars

Round-trip from

$251
(Air Canada)

One-way from

$103
(Flightnetwork)

Popular in

December

Cheapest in

November

Average price

$553

Good round-trip deal

$488 or less

Good one-way deal

$165 or less
Provider with most accurate pricing for Seattle/Tacoma Intl-Toronto (YTO) flight deals.
Search Deals
Provider most trusted by Cheapflights users for Seattle/Tacoma Intl-Toronto (YTO) flights.
Search Deals
From Seattle/Tacoma Intl to Ontario
Search Deals
One-way flight from Seattle/Tacoma Intl to Ontario
Search Deals
High demand for flights, 7% potential price rise
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($15 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 2,558,603 searches. Data last updated December 12, 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 - YKF

SEAYKF

Seattle/Tacoma Intl

Tue 5/12

7:05 am-12:45 am

1 stop14h 40m

Toronto Region of Waterloo Intl

Tue 5/19

6:00 am-1:08 pm

1 stop10h 08m

$252

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Thu 2/12

7:55 am-3:35 pm

Nonstop4h 40m

Toronto Pearson Intl

Sat 3/7

4:45 pm-7:18 pm

Nonstop5h 33m

$262

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Fri 3/6

7:55 am-3:35 pm

Nonstop4h 40m

Toronto Pearson Intl

Mon 3/9

4:45 pm-7:18 pm

Nonstop5h 33m

$273

SeattleMontreal

SEA - YUL

SEAYUL

Seattle/Tacoma Intl

Sun 1/11

3:10 pm-7:05 am

1 stop12h 55m

Montreal Pierre Elliott Trudeau Intl

Tue 1/20

4:15 pm-2:20 pm

1 stop25h 05m

$275

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sat 1/24

6:48 am-10:37 pm

1 stop12h 49m

Toronto Pearson Intl

Sat 1/31

9:00 am-6:14 pm

1 stop12h 14m

$276

SeattleToronto

SEA - YKF

SEAYKF

Seattle/Tacoma Intl

Tue 5/26

7:05 am-12:45 am

1 stop14h 40m

Toronto Region of Waterloo Intl

Wed 6/3

6:00 am-8:28 pm

1 stop17h 28m

$276

SeattleToronto

SEA - YKF

SEAYKF

Seattle/Tacoma Intl

Sun 5/3

7:05 am-12:45 am

1 stop14h 40m

Toronto Region of Waterloo Intl

Fri 5/8

6:00 am-8:28 pm

1 stop17h 28m

$276

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Tue 1/20

5:00 am-3:02 pm

1 stop7h 02m

Toronto Pearson Intl

Tue 1/27

2:57 pm-11:15 pm

1 stop11h 18m

$281

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Thu 1/22

8:00 pm-8:46 am

2 stops9h 46m

London

Mon 1/26

5:40 pm-10:16 pm

1 stop7h 36m

$283

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Wed 1/7

5:00 am-3:02 pm

1 stop7h 02m

Toronto Pearson Intl

Wed 1/14

11:00 am-9:12 pm

2 stops13h 12m

$286

Flights are sorted by cheapest round-trip flights first.

Deals found on 12/11

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 $121). Flying from Seattle to Region of Ontario in December is currently the most expensive (average of $261). 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 December 12, 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 afternoon, which can drop the price by up to 50% versus a flight in the morning.

What is the cheapest day to fly from Seattle to Region of Ontario?

Use this chart to determine the cheapest time to fly round-trip from Seattle to Ontario. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their Seattle to Region of Ontario flight should consider departing on Wednesday evenings when fares are most often at their lowest. Sunday evenings flights should be avoided if possible as fares are typically the most expensive at this time.

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 December 12, 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 December 12, 2025.
Read through reviews of airlines operating flights from Seattle to Ontario, such as Alaska Airlines, Delta, and United Airlines. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
11,429 reviews

Boarding

8.1

Entertainment

7.0

Comfort

7.8

Crew

8.5

Overall

8.0

Food

7.1

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
11,429 reviews
Alaska Airlines
8.0
Very good
11,429 reviews

Boarding

8.1

Entertainment

7.0

Comfort

7.8

Crew

8.5

Overall

8.0

Food

7.1

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.
Delta
7.9
Good
8,008 reviews
Alaska Airlines
8.0
Very good
11,429 reviews

Boarding

8.1

Entertainment

7.0

Comfort

7.8

Crew

8.5

Overall

8.0

Food

7.1

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
11,429 reviews

Boarding

8.1

Entertainment

7.0

Comfort

7.8

Crew

8.5

Overall

8.0

Food

7.1

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
3,194 reviews
Alaska Airlines
8.0
Very good
11,429 reviews

Boarding

8.1

Entertainment

7.0

Comfort

7.8

Crew

8.5

Overall

8.0

Food

7.1

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
10,514 reviews
Alaska Airlines
8.0
Very good
11,429 reviews

Boarding

8.1

Entertainment

7.0

Comfort

7.8

Crew

8.5

Overall

8.0

Food

7.1

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?

    For a flight from Seattle to Ontario, you will be flying from Seattle/Tacoma Intl. Seattle/Tacoma Intl (SEA) is just 11.4 mi from the center of the city.

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

    Departing from Seattle to Region of Ontario will take you 4h 40m. The distance between Seattle and Region of Ontario is about 2054 mi. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

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

    To fly one-way, consider booking your trip with WestJet, which is currently one of the cheapest options available, starting at $83. Alaska Airlines flights start at $100 while deals on United Airlines start at $115 one-way.

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

    The most popular route from Seattle to Region of Ontario is Seattle/Tacoma Intl - Toronto Pearson Intl. You may also consider Seattle/Tacoma Intl - Montreal Pierre Elliott Trudeau Intl or Seattle/Tacoma Intl - Hamilton.

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

    The top 3 most reliable airlines when flying from Seattle to Region of Ontario are Alaska Airlines (96%), Qatar Airways (96%) and Hawaiian Airlines (94%).

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

    Looking for the cheapest flight from Seattle to Region of Ontario? While on average our users pay $1,089, our data indicates the cheapest price to be $111. The most popular route (Seattle/Tacoma Intl - Toronto Pearson Intl), is priced around $227.

  • 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 $121). Flying from Seattle to Region of Ontario in December is currently the most expensive (average of $261). 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 5 airlines flying from Seattle to Ontario

Discover the top 5 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 2,558,603 searches. Data last updated December 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$151Average$606FlexibilityNo cancel feeOn-time67%
United AirlinesCheapest$173Average$513FlexibilityNo cancel feeOn-time69%
DeltaCheapest$182Average$424FlexibilityNo cancel feeOn-timeN/A
WestJetCheapest$226Average$347FlexibilityNo cancel feeOn-time60%
Alaska AirlinesCheapest$254Average$471FlexibilityNo cancel feeOn-time75%

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