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

Return flights

28 Sep - 31 Oct	AJet
28 Sep - 30 Oct	AJet
11 Sep - 23 Oct	Pegasus Airlines
26 Sep - 28 Oct	AJet
18 Sep - 30 Oct	AJet
12 Sep - 30 Oct	Pegasus Airlines
07 Sep - 26 Oct	AJet
14 Sep - 31 Oct	Pegasus Airlines
14 Sep - 30 Oct	Pegasus Airlines
30 Sep - 30 Oct	Pegasus Airlines
20 Sep - 27 Sep	AJet
19 Sep - 27 Sep	AJet
23 Sep - 27 Sep	Pegasus Airlines
19 Sep - 22 Sep	AJet
20 Sep - 24 Sep	AJet
22 Sep - 27 Sep	AJet
16 Sep - 22 Sep	AJet
16 Sep - 24 Sep	AJet
26 Sep - 29 Sep	AJet
17 Sep - 22 Sep	AJet

Also check the deals for one-way flights from London to Bangkok 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 Bangkok in September from $485

Return flights