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

Return flights

04 Dec - 07 Dec	KLM
04 Dec - 10 Dec	KLM
04 Dec - 11 Dec	KLM
03 Dec - 09 Dec	Lufthansa
11 Dec - 16 Dec	KLM
09 Dec - 11 Dec	Lufthansa
02 Dec - 09 Dec	Lufthansa
10 Dec - 17 Dec	Lufthansa
17 Dec - 24 Dec	Lufthansa
15 Dec - 15 Jan	Lufthansa
03 Dec - 12 Dec	KLM
29 Dec - 07 Jan	Lufthansa
18 Dec - 11 Jan	KLM
25 Dec - 18 Jan	KLM
22 Dec - 05 Jan	Lufthansa
24 Dec - 01 Jan	KLM
31 Dec - 02 Jan	KLM
24 Dec - 02 Jan	ITA Airways
25 Dec - 02 Jan	ITA Airways
24 Dec - 04 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 $251

Return flights