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$101+ 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 12/6. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — YYZ
Nov 27 — Dec 41
Thu 11/27
Thu 12/4
1 adult, Economy
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Find 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 October 28, 2025.

This SmartFares deal was found by Cheapflights users on 10/26. 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 SmartFares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/297:57 amSEA - YYZ
Nonstop4h 38mAlaska Airlines
Sat 12/64:45 pmYYZ - SEA
Nonstop5h 33mAlaska Airlines
Deal found 10/26$224
This Trip.com deal was found by Cheapflights users on 10/26. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/33:15 pmSEA - YYZ
2 stops11h 43mWestJet
Wed 12/107:00 amYYZ - SEA
1 stop10h 20mWestJet
Deal found 10/26$227
This SmartFares deal was found by Cheapflights users on 10/27. 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 SmartFares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/297:57 amSEA - YYZ
Nonstop4h 38mAlaska Airlines
Tue 12/24:45 pmYYZ - SEA
Nonstop5h 33mAlaska Airlines
Deal found 10/27$229
This Kiwi.com deal was found by Cheapflights users on 10/27. 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.
Sat 11/2911:55 amSEA - YYZ
2 stops8h 44mWestJet
Tue 12/27:45 amYYZ - SEA
1 stop9h 35mWestJet
Deal found 10/27$232
This Kiwi.com deal was found by Cheapflights users on 10/26. 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.
Sat 12/611:55 amSEA - YYZ
2 stops8h 44mWestJet
Wed 12/107:45 amYYZ - SEA
1 stop9h 35mWestJet
Deal found 10/26$234
This Trip.com deal was found by Cheapflights users on 10/27. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/33:15 pmSEA - YYZ
2 stops11h 43mWestJet
Sun 12/77:45 amYYZ - SEA
1 stop9h 35mWestJet
Deal found 10/27$236
This FlightHub deal was found by Cheapflights users on 10/26. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 12/27:55 amSEA - YYZ
Nonstop4h 40mMultiple Airlines
Sun 12/77:45 amYYZ - SEA
1 stop9h 35mMultiple Airlines
Deal found 10/26$238
This Trip.com deal was found by Cheapflights users on 10/27. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/123:10 pmSEA - YYZ
2 stops11h 48mWestJet
Tue 12/167:45 amYYZ - SEA
1 stop9h 35mWestJet
Deal found 10/27$239
This Trip.com deal was found by Cheapflights users on 10/26. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/2911:55 amSEA - YYZ
2 stops8h 44mWestJet
Sat 12/610:15 pmYYZ - SEA
2 stops15h 07mWestJet
Deal found 10/26$240
This Trip.com deal was found by Cheapflights users on 10/26. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/297:57 amSEA - YYZ
Nonstop4h 38mMultiple Airlines
Sat 12/610:15 pmYYZ - SEA
2 stops15h 07mMultiple Airlines
Deal found 10/26$244
This FlightHub deal was found by Cheapflights users on 10/26. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/207:55 amSEA - YYZ
Nonstop4h 40mMultiple Airlines
Mon 11/247:45 amYYZ - SEA
1 stop9h 35mMultiple Airlines
Deal found 10/26$245
This Trip.com deal was found by Cheapflights users on 10/27. 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 Trip.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/43:10 pmSEA - YYZ
2 stops11h 48mWestJet
Sun 12/77:45 amYYZ - SEA
1 stop9h 35mWestJet
Deal found 10/27$247

Cheap flight deals from Seattle to Ontario

Keep the following information in mind while searching for Seattle to Ontario flight deals. Data was last updated October 28, 2025.

Most accurate provider

Mytrip
3 stars

Most trusted provider

Mytrip
3 stars

Round-trip from

$224
(SmartFares)

One-way from

$101
(Alaska Airlines)

Popular in

June

Cheapest in

January

Average price

$442

Good round-trip deal

$342 or less

Good one-way deal

$262 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
Highest demand for flights based on searches. 14% potential increase in price ($66 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($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
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 October 28, 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

Sat 11/15

7:55 am-3:35 pm

Nonstop4h 40m

Toronto Pearson Intl

Wed 11/19

4:45 pm-7:05 pm

Nonstop5h 20m

$251

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sat 12/6

7:55 am-3:35 pm

Nonstop4h 40m

Toronto Pearson Intl

Sat 12/13

4:45 pm-7:18 pm

Nonstop5h 33m

$251

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Wed 2/18

8:00 am-3:35 pm

Nonstop4h 35m

Toronto Pearson Intl

Sat 2/21

4:45 pm-7:05 pm

Nonstop5h 20m

$251

SeattleOttawa

SEA - YOW

SEAYOW

Seattle/Tacoma Intl

Tue 3/10

11:59 pm-10:26 am

1 stop7h 27m

Ottawa

Wed 3/11

2:15 pm-8:35 pm

1 stop9h 20m

$259

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Wed 2/18

8:00 am-3:35 pm

Nonstop4h 35m

Toronto Pearson Intl

Mon 2/23

4:45 pm-7:05 pm

Nonstop5h 20m

$262

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Wed 11/19

7:55 am-3:35 pm

Nonstop4h 40m

Toronto Pearson Intl

Fri 11/21

4:45 pm-7:17 pm

Nonstop5h 32m

$262

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sun 1/11

7:55 am-3:35 pm

Nonstop4h 40m

Toronto Pearson Intl

Sat 1/17

4:45 pm-7:21 pm

Nonstop5h 36m

$262

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sun 2/15

8:00 am-3:35 pm

Nonstop4h 35m

Toronto Pearson Intl

Tue 2/17

4:45 pm-7:05 pm

Nonstop5h 20m

$262

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Tue 3/10

8:00 am-3:35 pm

Nonstop4h 35m

Toronto Pearson Intl

Wed 3/11

4:45 pm-7:05 pm

Nonstop5h 20m

$273

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Mon 3/2

8:00 pm-8:46 am

2 stops9h 46m

London

Wed 3/4

5:40 pm-10:16 pm

1 stop7h 36m

$283

Flights are sorted by cheapest round-trip flights first.

Deals found on 10/25

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 May is currently the most expensive (average of $271). 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 October 28, 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.

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 October 28, 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
11,199 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
11,199 reviews
Alaska Airlines
8.0
Very good
11,199 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
7,995 reviews
Alaska Airlines
8.0
Very good
11,199 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
8,996 reviews
Alaska Airlines
8.0
Very good
11,199 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
3,148 reviews
Alaska Airlines
8.0
Very good
11,199 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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
10,370 reviews
Alaska Airlines
8.0
Very good
11,199 reviews

Overall

8.0

Comfort

7.8

Entertainment

7.0

Food

7.1

Boarding

8.1

Crew

8.5

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 Alaska Airlines, which is currently one of the cheapest options available, starting at $101. WestJet flights start at $130 while deals on Air Canada start at $143 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 Qatar Airways (97%), Alaska Airlines (97%) and Air Tahiti Nui (96%).

  • 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 $1,025, 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 May is currently the most expensive (average of $271). 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.

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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 October 28, 2025.
AirlineCheapestAverageFlexibilityOn-time
Air CanadaCheapest$165Average$558FlexibilityNo cancel feeOn-time67%
DeltaCheapest$182Average$433FlexibilityNo cancel feeOn-timeN/A
WestJetCheapest$222Average$351FlexibilityNo cancel feeOn-time60%
Alaska AirlinesCheapest$273Average$482FlexibilityNo cancel feeOn-time75%
United AirlinesCheapest$282Average$490FlexibilityNo cancel feeOn-time69%

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