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

Return flights

01 Sep - 08 Sep	IndiGo
12 Sep - 18 Sep	IndiGo
28 Sep - 05 Oct	IndiGo
28 Sep - 08 Oct	IndiGo
29 Sep - 15 Oct	IndiGo
27 Sep - 21 Oct	IndiGo
27 Sep - 18 Oct	IndiGo
15 Sep - 31 Oct	IndiGo
28 Sep - 12 Oct	IndiGo
27 Sep - 08 Oct	Thai Airways
27 Sep - 06 Oct	Etihad Airways
12 Sep - 29 Sep	KLM
27 Sep - 10 Oct	Thai Airways
01 Sep - 08 Sep	Finnair	direct
12 Sep - 18 Sep	Finnair	direct

Also check the deals for one-way flights from Bangkok 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 Bangkok to Helsinki in September from $796

Return flights