AirHint found the following cheapest return flights from Seattle (SEA) to Taipei (TPE) in September 2025 (see full year).

Return flights

08 Sep - 15 Sep	Asiana Airlines
16 Sep - 15 Oct	Asiana Airlines
24 Sep - 21 Oct	Asiana Airlines
24 Sep - 28 Oct	Asiana Airlines
24 Sep - 15 Oct	Asiana Airlines
17 Sep - 01 Oct	Philippine Airlines
16 Sep - 20 Sep	Asiana Airlines
23 Sep - 14 Oct	Korean Air
23 Sep - 21 Oct	Korean Air
19 Sep - 05 Oct	Philippine Airlines
08 Sep - 15 Sep	Delta	direct
09 Sep - 16 Sep	Delta	direct
24 Sep - 21 Oct	Delta	direct
24 Sep - 28 Oct	Delta	direct
24 Sep - 26 Sep	Delta	direct
26 Sep - 30 Sep	Delta	direct
20 Sep - 28 Sep	Delta	direct

Also check the deals for one-way flights from Seattle to Taipei in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Seattle to Taipei in September from $589

Return flights