AirHint found the following cheapest return flights from Washington (IAD) to Sydney (SYD) in December 2025 (see full year).

Return flights

03 Dec - 20 Jan	Air New Zealand
01 Dec - 16 Dec	Turkish Airlines
04 Dec - 26 Dec	Turkish Airlines
13 Dec - 30 Dec	Turkish Airlines
28 Dec - 11 Jan	Turkish Airlines
29 Dec - 11 Jan	Turkish Airlines
29 Dec - 09 Jan	Air New Zealand
27 Dec - 19 Jan	Turkish Airlines
14 Dec - 29 Dec	Turkish Airlines
16 Dec - 30 Dec	Air Canada
16 Dec - 29 Dec	Austrian Airlines
16 Dec - 31 Dec	Air New Zealand
18 Dec - 30 Dec	American Airlines
18 Dec - 09 Jan	Qatar Airways

Also check the deals for one-way flights from Washington to Sydney 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 Washington to Sydney in December from $1275

Return flights