AirHint found the following cheapest return flights from Seattle (SEA) to Singapore (SIN) in December 2025 (see full year).

Return flights

08 Dec - 13 Dec	Asiana Airlines
05 Dec - 14 Dec	Korean Air
05 Dec - 13 Dec	Asiana Airlines
05 Dec - 27 Dec	Singapore Airlines	direct
06 Dec - 13 Dec	Singapore Airlines	direct
30 Dec - 17 Jan	United
14 Dec - 28 Dec	Korean Air
05 Dec - 13 Dec	Singapore Airlines	direct
30 Dec - 17 Jan	Singapore Airlines	direct
05 Dec - 14 Dec	Singapore Airlines	direct
31 Dec - 10 Jan	Cathay Pacific
25 Dec - 05 Jan	Alaska Airlines
19 Dec - 01 Jan	WestJet
20 Dec - 03 Jan	Turkish Airlines
19 Dec - 04 Jan	Alaska Airlines
18 Dec - 02 Jan	Alaska Airlines
19 Dec - 01 Jan	Singapore Airlines	direct

Also check the deals for one-way flights from Seattle to Singapore in December.

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 Singapore in December from $798

Return flights