AirHint found the following cheapest return flights from London (LHR) to Sofia (SOF) in September 2025 (see full year).

Return flights

17 Sep - 10 Oct	Vueling Airlines
26 Sep - 30 Sep	Vueling Airlines
28 Sep - 05 Oct	British Airways	direct
16 Sep - 17 Sep	Lufthansa
16 Sep - 09 Oct	Vueling Airlines
16 Sep - 23 Sep	Lufthansa
27 Sep - 30 Sep	Vueling Airlines
02 Sep - 05 Sep	Lufthansa
17 Sep - 24 Sep	Lufthansa
15 Sep - 18 Sep	Lufthansa
04 Sep - 09 Sep	Lufthansa
04 Sep - 23 Sep	Lufthansa
22 Sep - 29 Sep	LOT
30 Sep - 01 Oct	Austrian Airlines
28 Sep - 04 Oct	LOT
30 Sep - 14 Oct	Austrian Airlines
07 Sep - 08 Oct	Austrian Airlines
27 Sep - 01 Oct	Austrian Airlines
29 Sep - 04 Oct	LOT
30 Sep - 04 Oct	LOT

Also check the deals for one-way flights from London to Sofia 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 Sofia in September from $204

Return flights