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$110+ 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 5/14. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — YYZ
May 28 — Jun 41
Thu 5/28
Thu 6/4
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 April 28, 2026.

This oojo deal was found by Cheapflights users on 4/23. 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 oojo is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/710:30 am
SEA
-
YYZ
1 stop9h 15m
WestJet
Fri 8/1412:00 pm
YYZ
-
SEA
1 stop9h 45m
WestJet
Deal found 4/23$265
This Trip.com deal was found by Cheapflights users on 4/23. 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.
Sun 7/127:35 pm
SEA
-
YYZ
1 stop15h 40m
WestJet
Tue 7/211:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Deal found 4/23$268
This FlightHub deal was found by Cheapflights users on 4/23. 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 9/17:00 am
SEA
-
YYZ
1 stop7h 10m
WestJet
Sun 9/63:50 pm
YYZ
-
SEA
1 stop8h 10m
WestJet
Deal found 4/23$269
This Kiwi.com deal was found by Cheapflights users on 4/23. 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.
Tue 6/2310:30 am
SEA
-
YYZ
1 stop10h 40m
WestJet
Thu 7/233:50 pm
YYZ
-
SEA
1 stop8h 10m
WestJet
Deal found 4/23$271
This Priceline deal was found by Cheapflights users on 4/23. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 8/77:00 am
SEA
-
YYZ
2 stops11h 10m
WestJet
Wed 8/1212:00 pm
YYZ
-
SEA
1 stop9h 45m
WestJet
Deal found 4/23$272
This Kiwi.com deal was found by Cheapflights users on 4/23. 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.
Fri 7/317:35 pm
SEA
-
YYZ
1 stop8h 20m
WestJet
Sun 8/910:50 am
YYZ
-
SEA
1 stop10h 55m
WestJet
Deal found 4/23$273
This FlightHub deal was found by Cheapflights users on 4/23. 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.
Fri 10/97:35 pm
SEA
-
YYZ
1 stop8h 20m
WestJet
Tue 10/1312:00 pm
YYZ
-
SEA
1 stop9h 45m
WestJet
Deal found 4/23$274
This Kiwi.com deal was found by Cheapflights users on 4/25. 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.
Fri 5/1510:30 am
SEA
-
YYZ
1 stop7h 45m
WestJet
Sun 5/176:10 am
YYZ
-
SEA
2 stops15h 35m
WestJet
Deal found 4/25$275
This Kiwi.com deal was found by Cheapflights users on 4/26. 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.
Mon 5/117:35 pm
SEA
-
YYZ
1 stop8h 20m
WestJet
Sat 5/1610:25 pm
YYZ
-
SEA
1 stop14h 15m
WestJet
Deal found 4/26$276
This Kiwi.com deal was found by Cheapflights users on 4/24. 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 5/2310:30 am
SEA
-
YYZ
1 stop10h 40m
WestJet
Thu 7/161:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Deal found 4/24$277
This Kiwi.com deal was found by Cheapflights users on 4/24. 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.
Thu 5/2110:30 am
SEA
-
YYZ
1 stop11h 35m
WestJet
Wed 7/151:30 pm
YYZ
-
SEA
1 stop8h 15m
WestJet
Deal found 4/24$278
This Kiwi.com deal was found by Cheapflights users on 4/23. 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.
Tue 5/1210:30 am
SEA
-
YYZ
2 stops10h 29m
WestJet
Sat 5/1610:25 pm
YYZ
-
SEA
1 stop14h 15m
WestJet
Deal found 4/23$279

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 April 28, 2026.

Most accurate provider

FlightHub
3 stars

Most trusted provider

FlightHub
3 stars

Round-trip from

$265
(oojo)

One-way from

$110
(Trip.com)

Popular in

June

Cheapest in

January

Average price

$379

Good round-trip deal

$486 or less

Good one-way deal

$298 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. 17% potential increase in price ($80 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($11 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in April 2026
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 April 28, 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

SeattleLondon

SEA - YXU

SEAYXU

Seattle/Tacoma Intl

Wed 8/19

7:00 am-4:45 pm

1 stop6h 45m

London

Sat 8/22

5:55 pm-6:45 pm

1 stop27h 50m

$316

SeattleMontreal

SEA - YUL

SEAYUL

Seattle/Tacoma Intl

Sat 7/4

10:30 am-11:45 pm

1 stop10h 15m

Montreal Pierre Elliott Trudeau Intl

Wed 7/8

6:45 am-6:45 pm

2 stops15h 00m

$319

SeattleToronto

SEA - YKF

SEAYKF

Seattle/Tacoma Intl

Thu 6/18

7:00 am-7:50 pm

1 stop9h 50m

Toronto Region of Waterloo Intl

Tue 6/23

8:40 pm-9:40 am

1 stop16h 00m

$322

SeattleToronto

SEA - YKF

SEAYKF

Seattle/Tacoma Intl

Thu 6/18

7:00 am-7:50 pm

1 stop9h 50m

Toronto Region of Waterloo Intl

Mon 6/29

8:40 pm-9:40 am

1 stop16h 00m

$326

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sat 5/23

11:05 pm-1:30 pm

1 stop11h 25m

Toronto Pearson Intl

Mon 6/1

5:45 pm-12:10 am

1 stop9h 25m

$336

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Sun 5/24

11:05 pm-1:30 pm

1 stop11h 25m

Toronto Pearson Intl

Thu 5/28

12:09 pm-8:41 pm

1 stop11h 32m

$336

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Thu 6/4

11:05 pm-1:30 pm

1 stop11h 25m

Toronto Pearson Intl

Sun 6/7

1:40 pm-11:59 pm

1 stop13h 19m

$336

SeattleToronto

SEA - YYZ

SEAYYZ

Seattle/Tacoma Intl

Wed 5/27

11:05 pm-8:59 am

1 stop6h 54m

Toronto Pearson Intl

Mon 6/1

6:10 am-11:05 am

1 stop7h 55m

$336

SeattleToronto

SEA - YKF

SEAYKF

Seattle/Tacoma Intl

Fri 6/12

7:35 pm-7:50 pm

1 stop21h 15m

Toronto Region of Waterloo Intl

Fri 6/19

8:40 pm-9:40 am

1 stop16h 00m

$341

SeattleToronto

SEA - YKF

SEAYKF

Seattle/Tacoma Intl

Thu 6/4

7:35 pm-7:50 pm

1 stop21h 15m

Toronto Region of Waterloo Intl

Sun 6/7

8:40 pm-9:40 am

1 stop16h 00m

$341

Flights are sorted by cheapest round-trip flights first.

Deals found on 4/27

Showing 1-10 of 60 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 Region of Ontario?

The price you pay for your flight from Seattle to Region of Ontario may vary depending on when you book. For the best chance of a lower fare, look to book 64 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

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

Currently, November is the cheapest month in which you can book a flight from Seattle to Region of Ontario (average of $88). Flying from Seattle to Region of Ontario in June is currently the most expensive (average of $165). 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 April 28, 2026.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Seattle to Region of Ontario as you normally would.

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 April 28, 2026.

The most flights from SEA to CAON are scheduled on a Monday (5 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (2 on average).

How much does it cost to fly round-trip from Seattle to Region of 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 April 28, 2026.
Read through reviews of airlines operating flights from Seattle to Ontario, such as Alaska Airlines,Delta, andUnited Airlines. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
7.9
Good
12,313 reviews

Comfort

7.8

Overall

7.9

Crew

8.5

Food

7.0

Boarding

8.1

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
Alaska Airlines
7.9
Good
12,313 reviews
Alaska Airlines
7.9
Good
12,313 reviews

Comfort

7.8

Overall

7.9

Crew

8.5

Food

7.0

Boarding

8.1

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
Delta
7.9
Good
8,467 reviews
Alaska Airlines
7.9
Good
12,313 reviews

Comfort

7.8

Overall

7.9

Crew

8.5

Food

7.0

Boarding

8.1

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
United Airlines
7.4
Good
9,680 reviews
Alaska Airlines
7.9
Good
12,313 reviews

Comfort

7.8

Overall

7.9

Crew

8.5

Food

7.0

Boarding

8.1

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
WestJet
7.2
Good
3,328 reviews
Alaska Airlines
7.9
Good
12,313 reviews

Comfort

7.8

Overall

7.9

Crew

8.5

Food

7.0

Boarding

8.1

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.
Air Canada
7.1
Good
10,979 reviews
Alaska Airlines
7.9
Good
12,313 reviews

Comfort

7.8

Overall

7.9

Crew

8.5

Food

7.0

Boarding

8.1

Entertainment

7.0

Reviews

1 / 20
4.0
Okay

Anonymous,Dec 2025

SEA - MSY

I really got a lesson in upgrades. I let my seat get chosen . Both times a middle seat...on purpose ...even when we were not full. That's petty I sat behind the first class . They got more than 1 drink ...and a snack . .and the staff actually talked to them...behind a see thru shawl/sheet in the aisle....... You could see over the seats just fine and you could hear the voices just fine. But the sheet let You KNOW. Your not welcome here. For a moment I regretted not spending 300 dollars per seat so I could see a smile and eat a sandwhich and enjoy my seat . The married couple drank champain and laughed and flirted with each other. It looked so happy and care free MONEY really does buy happiness ..the hateful glares and sighs from my seat mates brought me back to reality I wasn't rich and I still had 2 hours left in this middle seat.

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 6h 45m. The distance between Seattle and Region of Ontario is about 2000 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 $80. WestJet flights start at $83 while deals on Air Canada start at $99 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 - Toronto Island.

  • 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 Air Tahiti Nui (100%), Alaska Airlines (92%) and Hawaiian Airlines (92%).

  • 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 $928, our data indicates the cheapest price to be $140. The most popular route (Seattle/Tacoma Intl - Toronto Pearson Intl), is priced around $270.

  • 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, November is the cheapest month in which you can book a flight from Seattle to Region of Ontario (average of $88). Flying from Seattle to Region of Ontario in June is currently the most expensive (average of $165). 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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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 April 28, 2026.
AirlineCheapestAverageFlexibilityOn-time
DeltaCheapest$138Average$403FlexibilityNo cancel feeOn-timeN/A
Air CanadaCheapest$150Average$547FlexibilityNo cancel feeOn-time67%
WestJetCheapest$222Average$347FlexibilityNo cancel feeOn-time60%
United AirlinesCheapest$238Average$500FlexibilityNo cancel feeOn-time69%
Alaska AirlinesCheapest$251Average$445FlexibilityNo cancel feeOn-time75%

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