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

Return flights

01 Dec - 25 Jan	China Southern
04 Dec - 31 Jan	China Southern
01 Dec - 31 Jan	China Southern
07 Dec - 18 Jan	China Eastern
02 Dec - 29 Jan	China Eastern
03 Dec - 13 Jan	China Eastern
01 Dec - 19 Jan	China Southern
01 Dec - 08 Dec	China Southern
02 Dec - 09 Dec	China Southern
02 Dec - 14 Dec	China Southern
02 Dec - 31 Jan	China Southern
04 Dec - 17 Jan	China Southern
05 Dec - 22 Jan	Shenzhen Airlines
03 Dec - 10 Dec	China Southern
04 Dec - 11 Dec	Air China
01 Dec - 04 Dec	China Southern
01 Dec - 09 Dec	China Southern
01 Dec - 11 Dec	Air China
03 Dec - 07 Dec	Air China
02 Dec - 16 Dec	China Southern

Also check the deals for one-way flights from London 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 London to Sydney in December from $830

Return flights