HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Seattle

$88+ Cheap flights from Ontario to Seattle (ONT - SEA)

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 10/27. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — SEA
Oct 19 — Oct 261
Sun 10/19
Sun 10/26
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from Ontario to Seattle with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheapflights Tip: The best prices from Ontario to Seattle/Tacoma Intl are usually found in January or February, booked 90 days in advance, depart on a Friday or Thursday and return on a Thursday

Cheap flight deals from Ontario to Seattle

Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to Seattle (SEA). 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 September 19, 2025.

Round-trip from

$122
(CheapOair)

One-way from

$88
(Gotogate)

Popular in

July

Cheapest in

January

Average price

$201

Good round-trip deal

$181 or less

Good one-way deal

$124 or less
From Ontario to Seattle/Tacoma Intl
Search Deals
One-way flight from Ontario to Seattle/Tacoma Intl
Search Deals
Highest demand for flights based on searches. 12% potential increase in price ($29 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($5 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in September 2025
Search Deals
Price to beat on a round-trip flight from Ontario to Seattle/Tacoma Intl.
Search Deals
Price to beat on a one-way flight from Ontario to Seattle/Tacoma Intl.
Search Deals

Find flight deals from Ontario to Seattle

Cheapest flights from Ontario to Seattle
Explore the most affordable flight options available from Ontario to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 19, 2025.

This Cheapflightsfares deal was found by Cheapflights users on 9/15. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/318:02 amONT - SEA
Nonstop2h 53mFrontier
Fri 11/77:17 pmSEA - ONT
Nonstop2h 41mFrontier
Deal found 9/15$118
This CheapOair deal was found by Cheapflights users on 9/16. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/2410:30 amONT - SEA
Nonstop2h 56mFrontier
Mon 10/278:28 amSEA - ONT
Nonstop2h 40mFrontier
Deal found 9/16$122
This Mytrip deal was found by Cheapflights users on 9/16. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 11/112:05 pmONT - SEA
1 stop25h 08mFrontier
Sun 11/27:17 pmSEA - ONT
Nonstop2h 41mFrontier
Deal found 9/16$123
This Mytrip deal was found by Cheapflights users on 9/18. 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/28:02 amONT - SEA
Nonstop2h 53mFrontier
Sun 11/97:17 pmSEA - ONT
Nonstop2h 41mFrontier
Deal found 9/18$124
This Priceline deal was found by Cheapflights users on 9/17. 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 10/1010:30 amONT - SEA
Nonstop2h 56mFrontier
Sun 12/142:36 pmSEA - ONT
Nonstop2h 36mFrontier
Deal found 9/17$125
This Booking.com deal was found by Cheapflights users on 9/17. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/2610:30 amONT - SEA
Nonstop2h 56mFrontier
Fri 10/317:17 pmSEA - ONT
Nonstop2h 41mFrontier
Deal found 9/17$129
This CheapOair deal was found by Cheapflights users on 9/18. 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/1210:30 amONT - SEA
Nonstop2h 56mFrontier
Sun 10/198:28 amSEA - ONT
Nonstop2h 40mFrontier
Deal found 9/18$131
This Delta deal was found by Cheapflights users on 9/16. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/165:50 pmONT - SEA
Nonstop2h 59mDelta
Tue 10/212:24 pmSEA - ONT
Nonstop2h 46mDelta
Deal found 9/16$133
This Delta deal was found by Cheapflights users on 9/16. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/75:50 pmONT - SEA
Nonstop2h 59mDelta
Sun 11/92:19 pmSEA - ONT
Nonstop2h 50mDelta
Deal found 9/16$134
This Cheapflightsfares deal was found by Cheapflights users on 9/18. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/1710:30 amONT - SEA
Nonstop2h 56mFrontier
Sun 10/198:28 amSEA - ONT
Nonstop2h 40mFrontier
Deal found 9/18$135
This Frontier deal was found by Cheapflights users on 9/18. 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 11/78:02 amONT - SEA
Nonstop2h 53mFrontier
Sun 11/97:17 pmSEA - ONT
Nonstop2h 41mFrontier
Deal found 9/18$136
This Cheapflightsfares deal was found by Cheapflights users on 9/16. 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 Cheapflightsfares is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 10/58:13 amONT - SEA
Nonstop2h 58mFrontier
Sun 10/128:28 amSEA - ONT
Nonstop2h 40mFrontier
Deal found 9/16$138

Cheapflights Fare Finder

 
Customize your flight search to find flights from Ontario to Seattle 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 September 19, 2025.
Use the filters below to find and compare flights from Ontario to Seattle that are best for you.

Fly from

Ontario

Fly to

Seattle

Route

Depart

Return

Price

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Sat 10/18

5:50 pm-8:49 pm

Nonstop2h 59m

Seattle/Tacoma Intl

Sat 10/25

2:24 pm-5:10 pm

Nonstop2h 46m

$133

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Fri 10/17

4:35 pm-11:59 pm

1 stop7h 24m

Seattle/Tacoma Intl

Sun 10/19

8:15 am-11:08 am

Nonstop2h 53m

$143

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Wed 10/15

5:50 pm-8:49 pm

Nonstop2h 59m

Seattle/Tacoma Intl

Sat 10/18

7:10 am-12:14 pm

1 stop5h 04m

$143

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Fri 10/17

4:35 pm-10:22 pm

1 stop5h 47m

Seattle/Tacoma Intl

Wed 10/22

5:25 am-12:14 pm

1 stop6h 49m

$153

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Tue 1/6

6:45 am-9:49 am

Nonstop3h 04m

Seattle/Tacoma Intl

Mon 1/12

7:55 pm-10:38 pm

Nonstop2h 43m

$155

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Wed 10/8

6:00 am-8:45 am

Nonstop2h 45m

Seattle/Tacoma Intl

Sat 10/11

9:25 pm-12:03 am

Nonstop2h 38m

$177

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Sat 11/8

6:00 am-8:50 am

Nonstop2h 50m

Seattle/Tacoma Intl

Sat 11/15

6:15 pm-8:53 pm

Nonstop2h 38m

$177

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Wed 1/14

6:00 am-8:50 am

Nonstop2h 50m

Seattle/Tacoma Intl

Sat 1/17

3:45 pm-6:17 pm

Nonstop2h 32m

$177

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Wed 10/22

7:35 am-10:35 am

Nonstop3h 00m

Seattle/Tacoma Intl

Tue 10/28

2:24 pm-5:10 pm

Nonstop2h 46m

$177

OntarioSeattle

ONT - SEA

ONTSEA

Ontario

Thu 10/23

7:35 am-10:35 am

Nonstop3h 00m

Seattle/Tacoma Intl

Sun 10/26

8:15 am-11:08 am

Nonstop2h 53m

$185

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/18

Showing 1-10 of 23 results
1
2
3

The best insider tips for Ontario to Seattle flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
Cheapflights partnered with top experts to bring you the best recommendations for your Ontario to Seattle trip
Airlines
Frontier

Frontier offers extra comfort seats with 32” separation for a fee, ideal for taller passengers.


Frontier's Board First option allows early boarding for carry-on bag purchasers and elite members.

Read more about Frontierby Marisa Garcia
Alaska Airlines

Alaska Airlines offers Wi-Fi for a flat fee, ideal for business travelers needing connectivity.


Alaska's Premium Class offers extra legroom and free cocktails, enhancing comfort on short flights.

Read more about Alaska Airlinesby Robert Schrader
Airports
ONT

ONT offers quick security checks compared to LAX, making it ideal for business travelers seeking efficiency.

Read more about ONTby Bill Fink
SEA

Use the Link light rail for a cost-effective trip to downtown Seattle, taking less than 40 minutes from SEA.

Read more about SEAby Brandon Schultz
Our travel experts
Marisa Garcia

Marisa Garcia

Expert on Frontier

Marisa Garcia

Marisa Garcia

Marisa knows planes inside and out, spending 16 years working on aircraft in hangars at airports around the world. She is an aviation industry expert, specialized in airline interiors and regulations. Ten years ago, she pivoted to journalism. She shares her insights in leading aviation, travel, and business publications and on her site FlightChic.

Read more
Robert Schrader

Robert Schrader

Expert on Alaska Airlines

Robert Schrader

Robert Schrader

One of the web's original travel bloggers, Robert launched his first site Leave Your Daily Hell in 2009. Since then, he's expanded into destination niche sites (one each for Japan, Thailand and Taiwan), in addition to having written for the inflight magazines of Singapore Airlines and Korean Air. Overall, he's visited nearly 100 countries, and flies business as often as possible.

Read more
Bill Fink

Bill Fink

Expert on ONT

Bill Fink

Bill Fink

Bill is an award-winning travel writer with extensive credits covering airlines and the aviation industry for publications including AARP, AFAR, The Points Guy and Yahoo. Based in Portland, Oregon, Bill has traveled to more than 75 countries - and been late for his flight in most of them. He once achieved top-level frequent flier status for all of American, Delta and United Airlines during a single year.

Read more
Brandon Schultz

Brandon Schultz

Expert on SEA

Brandon Schultz

Brandon Schultz

Brandon Schultz is an award-winning food and travel writer based in New York City. His work has appeared in Forbes, AAA, Thrillist, Travel + Leisure, and The Daily Meal, among many others, and he is the author of 6 books, including 3 cookbooks.

Read more

Best time to book a flight from Ontario to Seattle

Have a flexible travel schedule? Discover the best time to fly to Seattle from Ontario 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 Ontario to Seattle

How far ahead should I book a flight from Ontario to Seattle?

Use this chart to determine the optimal time to book a round-trip flight from Ontario to Seattle. Price data was last updated on September 12, 2025.

To ensure you get the cheapest price possible for a flight from Ontario to Seattle, you should look to book at least 90 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.

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

Currently, January is the cheapest month in which you can book a flight from Ontario to Seattle (average of $238). Flying from Ontario to Seattle in June is currently the most expensive (average of $387). 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 ONT to SEA?

Find hourly flight availability from Ontario to Seattle. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated September 19, 2025.

It’s typically best to fly out from Ontario to Seattle in the morning. Doing so could potentially save you 22% on the flight price compared to flying at noon, which is usually more expensive.

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

Use this chart to determine the cheapest time to fly round-trip from Ontario to Seattle. Price data was last updated on September 14, 2025.

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

Reviews of airlines servicing Seattle

Get insights into the airlines that provide service to Seattle. 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 Seattle. Reviews last updated September 19, 2025.
See what other customers who have flown with Alaska Airlines, Southwest, and Delta from Ontario to Seattle have to say. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
Southwest
8.0
Very good
4,242 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
Delta
8.0
Very good
7,964 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
Hawaiian Airlines
7.8
Good
2,732 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why
Frontier
5.8
Fair
3,171 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Food

7.1

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Anonymous,Aug 2025

MFR - SEA

Great smooth flight. Was hour and half late though. Don't know why

Related info for your journey

Find useful and relevant information for your journey from Ontario to Seattle. 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 Ontario to Seattle?

    If you wish to fly to Seattle from Ontario, then you need to book flights from Ontario to Seattle/Tacoma Intl. There are 16 flights from Ontario (ONT) to Seattle/Tacoma Intl (SEA) per day to choose from. Flights to Seattle from Ontario are available from 5 different airlines, which means you should have some options if you want to compare airfare deals. 2h 43m is how long a nonstop flight from Ontario to Seattle/Tacoma Intl typically takes.

  • How popular is this Ontario to Seattle flight route?

    The Ontario to Seattle/Tacoma Intl flight path was viewed by 251 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

  • How long is the flight from Ontario to Seattle?

    There are many flights that can get you from Ontario to Seattle in 2h 59m. Fly via Delta to get the fastest option. There are 956 mi between Ontario and Seattle. Most flights are nonstop.

  • What are the cheapest airlines flying from Ontario to Seattle round-trip?

    Cheapflights users have booked flights from Ontario to Seattle round-trip from $77. Other airlines that can offer you cheap pricing are Hawaiian Airlines, from $98, and Delta, from $117. You may be able to fly from Ontario to Seattle for 62% less than the average price by searching for these airlines.

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

    The cheapest airlines for a one-way flight from Ontario to Seattle are United Airlines ($89), Southwest ($89), and Delta ($91).

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

    Consider Scandinavian Airlines (95%), Japan Airlines (95%) or Frontier (95%) when booking your flight. These represent the most reliable airlines when flying from Ontario to Seattle.

  • What are the cheapest flights from Ontario to Seattle?

    While on average a flight from Ontario to Seattle is generally $392, our data shows the cheapest flight currently is $69. When looking at the most popular route, (Ontario - Seattle/Tacoma Intl), you can expect to pay $115 for that flight.

  • Can I find deals for flights from Ontario to Seattle that include hotel bookings?

    Yes. In addition to deals on Ontario to Seattle flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Ontario to Seattle?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Ontario to Seattle.

  • Can I find deals for business class flights from Ontario to Seattle?

    Yes. Cheapflights offers flight deals from Ontario to Seattle 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 Ontario to Seattle?

    Currently, January is the cheapest month in which you can book a flight from Ontario to Seattle (average of $238). Flying from Ontario to Seattle in June is currently the most expensive (average of $387). 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

Traveling to a place near Seattle?

Book flights to Seattle if you plan to visit one of these locations
SeaTac
Tukwila
Tacoma
Lakewood
Ocean Shores
Lynnwood
Edmonds
Leavenworth
Renton
Lacey
Olympia
Kent
Federal Way
Cle Elum
Puyallup
Chehalis
Kirkland
Issaquah
Aberdeen
Shoreline

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 Ontario to Seattle

See prices for flight routes from nearby airports that may be better suited for you.
Los Angeles to Seattle flights
San Francisco to Seattle flights
Los Angeles to Portland flights
Santa Ana to Seattle flights
San Jose to Seattle flights
San Diego to Seattle flights
Ontario to Portland flights
Burbank to Seattle flights
San Francisco to Portland flights
Las Vegas to Seattle flights
Santa Ana to Portland flights
Los Angeles to Everett flights
Oakland to Seattle flights
Sacramento to Seattle flights
Oakland to Portland flights
Burbank to Portland flights
San Diego to Portland flights
San Francisco to Everett flights
San Jose to Portland flights
San Diego to Everett flights
Las Vegas to Portland flights
Las Vegas to Everett flights
Sacramento to Portland flights
Long Beach to Seattle flights
San Luis Obispo to Seattle flights
Fresno to Seattle flights
Santa Ana to Everett flights
Palm Springs to Seattle flights
Santa Rosa to Seattle flights
San Francisco to Spokane flights
Fresno to Portland flights
Santa Barbara to Seattle flights
Los Angeles to Spokane flights
Reno to Portland flights
Palm Springs to Portland flights
Long Beach to Portland flights
Santa Rosa to Portland flights
Santa Barbara to Portland flights
Monterey to Seattle flights
San Diego to Spokane flights
Reno to Seattle flights
San Jose to Everett flights
Medford to Seattle flights
San Luis Obispo to Portland flights
Santa Ana to Spokane flights
Ontario to Spokane flights
Sacramento to Spokane flights
Medford to Portland flights
Los Angeles to Pasco flights

Top 5 airlines flying from Ontario to Seattle

Discover the top 5 airlines that operate flights from Ontario to Seattle. 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 September 19, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$77Average$168FlexibilityNo cancel feeOn-time62%
Hawaiian AirlinesCheapest$98Average$249FlexibilityNo cancel feeOn-time85%
DeltaCheapest$117Average$254FlexibilityNo cancel feeOn-timeN/A
Alaska AirlinesCheapest$149Average$265FlexibilityNo cancel feeOn-time75%
SouthwestCheapest$150Average$268FlexibilityNo cancel feeOn-time63%

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.