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

Return flights

07 Dec - 14 Dec	Qantas
02 Dec - 14 Dec	Qantas
02 Dec - 23 Dec	Qantas
10 Dec - 23 Dec	Qantas
09 Dec - 13 Dec	Qantas
02 Dec - 04 Dec	Qantas
02 Dec - 13 Dec	Qantas
01 Dec - 28 Dec	United
03 Dec - 23 Dec	United
03 Dec - 24 Dec	United
24 Dec - 14 Jan	Qantas
31 Dec - 22 Jan	Qantas
10 Dec - 07 Jan	Qantas
07 Dec - 09 Jan	United
23 Dec - 13 Jan	Frontier Airlines
07 Dec - 04 Jan	Frontier Airlines
19 Dec - 10 Jan	Frontier Airlines
16 Dec - 06 Jan	Alaska Airlines
17 Dec - 12 Jan	Hawaiian Airlines
24 Dec - 05 Jan	United

Also check the deals for one-way flights from Philadelphia 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 Philadelphia to Sydney in December from $833

Return flights