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

Return flights

08 Sep - 14 Oct	United
01 Sep - 21 Sep	Korean Air
17 Sep - 25 Sep	Korean Air
03 Sep - 24 Sep	Korean Air
25 Sep - 07 Oct	Korean Air
24 Sep - 28 Sep	Asiana Airlines
12 Sep - 28 Sep	Korean Air
13 Sep - 29 Sep	Korean Air
26 Sep - 08 Oct	Korean Air
12 Sep - 28 Sep	Philippine Airlines	direct
03 Sep - 24 Sep	Philippine Airlines	direct
24 Sep - 28 Sep	Philippine Airlines	direct
26 Sep - 08 Oct	Philippine Airlines	direct

Also check the deals for one-way flights from Seattle to Manila 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 Manila in September from 601€

Return flights