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

Return flights

14 Sep - 21 Sep	Asiana Airlines
21 Sep - 26 Sep	Asiana Airlines
08 Sep - 14 Oct	Asiana Airlines
04 Sep - 18 Sep	Delta	direct
08 Sep - 25 Sep	Delta	direct
24 Sep - 21 Oct	Delta	direct
24 Sep - 28 Oct	Delta	direct
23 Sep - 21 Oct	Delta	direct
16 Sep - 15 Oct	Delta	direct
24 Sep - 15 Oct	Delta	direct
08 Sep - 14 Oct	Delta	direct
14 Sep - 21 Sep	Delta	direct
20 Sep - 29 Sep	Delta	direct
21 Sep - 26 Sep	Delta	direct
20 Sep - 27 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 536€

Return flights