Cheap flights from Boston to Eastside from CA $128

View CA $128 flight on Thu, Sep. 25, 2025Opens in a new window

Popular airlines from Boston to Eastside

  • Alaska Airlines

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  • JetBlue Airways

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  • Sun Country Airlines

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  • American Airlines

    American Airlines

  • Delta

    Delta

  • United

    United

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Cheap flights from Boston (BOS) to Eastside (SEA)

Prices were available within the past 7 days and start at CA $128 for one-way flights and CA $258 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

American Airlines
Thu, Sep. 25 - Tue, Sep. 30
BOS
Boston
SEA
Seattle
CA $258 Roundtrip, found 6 hours ago
CA $258
Roundtrip
found 6 hours ago
Select American Airlines flight, departing Thu, Sep. 25 from Boston to Seattle, returning Tue, Sep. 30, priced at CA $258 found 6 hours ago
American Airlines
Thu, Sep. 25 - Tue, Sep. 30
BOS
Boston
SEA
Seattle
CA $277 Roundtrip, found 6 hours ago
CA $277
Roundtrip
found 6 hours ago
Select American Airlines flight, departing Thu, Sep. 25 from Boston to Seattle, returning Tue, Sep. 30, priced at CA $277 found 6 hours ago
JetBlue Airways
Thu, Sep. 25 - Tue, Sep. 30
BOS
Boston
SEA
Seattle
CA $290 Roundtrip, found 6 hours ago
CA $290
Roundtrip
found 6 hours ago
Select JetBlue Airways flight, departing Thu, Sep. 25 from Boston to Seattle, returning Tue, Sep. 30, priced at CA $290 found 6 hours ago
Alaska Airlines
Thu, Sep. 25 - Tue, Sep. 30
BOS
Boston
SEA
Seattle
CA $292 Roundtrip, found 6 hours ago
CA $292
Roundtrip
found 6 hours ago
Select Alaska Airlines flight, departing Thu, Sep. 25 from Boston to Seattle, returning Tue, Sep. 30, priced at CA $292 found 6 hours ago
Delta
Sat, Aug. 30 - Thu, Sep. 4
BOS
Boston
SEA
Seattle
CA $315 Roundtrip, found 5 days ago
CA $315
Roundtrip
found 5 days ago
Select Delta flight, departing Sat, Aug. 30 from Boston to Seattle, returning Thu, Sep. 4, priced at CA $315 found 5 days ago
Sun Country Airlines
Mon, Dec. 15 - Thu, Dec. 25
BOS
Boston
SEA
Seattle
CA $528 Roundtrip, found 23 hours ago
CA $528
Roundtrip
found 23 hours ago
Select Sun Country Airlines flight, departing Mon, Dec. 15 from Boston to Seattle, returning Thu, Dec. 25, priced at CA $528 found 23 hours ago

Find the cheapest month to fly from Boston (BOS) to Seattle (SEA)

September is typically the cheapest month to fly

From CA $212 - CA $336 per traveller.

Graph displaying average flight prices per month

*Available to Expedia members.