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

Return flights

01 Sep - 01 Oct	KLM
01 Sep - 11 Sep	KLM
16 Sep - 23 Sep	Lufthansa
17 Sep - 24 Sep	Lufthansa
15 Sep - 23 Sep	Lufthansa
09 Sep - 25 Sep	Lufthansa
23 Sep - 25 Sep	Lufthansa
15 Sep - 25 Sep	Lufthansa
18 Sep - 25 Sep	Lufthansa
09 Sep - 24 Sep	Lufthansa
01 Sep - 04 Sep	KLM
30 Sep - 07 Oct	Lufthansa
29 Sep - 07 Oct	Lufthansa
29 Sep - 06 Oct	Lufthansa
05 Sep - 03 Oct	Lufthansa
26 Sep - 03 Oct	Lufthansa
25 Sep - 01 Oct	Lufthansa
24 Sep - 01 Oct	Lufthansa
19 Sep - 01 Oct	KLM
17 Sep - 10 Oct	Lufthansa

Also check the deals for one-way flights from London to Istanbul in September.

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 September from $307

Return flights