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

Return flights

02 Dec - 10 Dec	Air Serbia
03 Dec - 05 Dec	Air Serbia
02 Dec - 04 Dec	Air Serbia
04 Dec - 06 Dec	Air Serbia
05 Dec - 07 Dec	Air Serbia
05 Dec - 06 Dec	Air Serbia
04 Dec - 19 Jan	Air Serbia
09 Dec - 26 Jan	Air Serbia
03 Dec - 06 Dec	Air Serbia
09 Dec - 13 Dec	Air Serbia
05 Dec - 13 Dec	Air Serbia
02 Dec - 05 Dec	Air Serbia
31 Dec - 31 Jan	KLM
30 Dec - 15 Jan	British Airways	direct
09 Dec - 26 Jan	British Airways	direct
11 Dec - 08 Jan	British Airways	direct
29 Dec - 21 Jan	Air France
04 Dec - 19 Jan	British Airways	direct
31 Dec - 31 Jan	British Airways	direct
11 Dec - 24 Jan	KLM

Also check the deals for one-way flights from London to Istanbul 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 Istanbul in December from $185

Return flights