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

Return flights

02 Sep - 05 Sep	KLM
09 Sep - 12 Sep	KLM
08 Sep - 12 Sep	KLM
20 Sep - 23 Sep	KLM
20 Sep - 26 Sep	KLM
22 Sep - 29 Sep	KLM
25 Sep - 28 Sep	KLM
05 Sep - 10 Sep	KLM
27 Sep - 29 Sep	KLM
26 Sep - 29 Sep	KLM
27 Sep - 05 Oct	KLM
30 Sep - 03 Oct	KLM
29 Sep - 03 Oct	KLM
26 Sep - 02 Oct	KLM
29 Sep - 02 Oct	KLM
01 Sep - 10 Oct	Lufthansa

Also check the deals for one-way flights from London to Helsinki 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 Helsinki in September from $257

Return flights