Cheapest one-way flights from Seattle to Sydney in December from $496

AirHint found the following cheapest one-way flights from Seattle (SEA) to Sydney (SYD) in December 2025 (see full year).

One-Way flights

08 Dec Hawaiian Airlines
02 Dec Hainan Airlines
03 Dec Hawaiian Airlines
09 Dec Hainan Airlines
29 Dec Delta
12 Dec Qantas
16 Dec WestJet
13 Dec Alaska Airlines
21 Dec Frontier Airlines
20 Dec Frontier Airlines

Also check the deals for return flights from Seattle to Sydney in December.

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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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