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

Return flights

30 Sep - 08 Oct	TAP
30 Sep - 05 Oct	TAP
30 Sep - 06 Oct	Ryanair
24 Sep - 01 Oct	Vueling Airlines
23 Sep - 30 Sep	Ryanair
27 Sep - 01 Oct	Air Europa
09 Sep - 11 Oct	Vueling Airlines
13 Sep - 17 Sep	Ryanair
29 Sep - 01 Oct	Ryanair
17 Sep - 24 Sep	easyJet
17 Sep - 20 Sep	easyJet
18 Sep - 20 Sep	Ryanair
19 Sep - 28 Sep	Ryanair
20 Sep - 27 Sep	Ryanair
15 Sep - 17 Sep	Ryanair
17 Sep - 18 Sep	easyJet
13 Sep - 18 Sep	Ryanair
06 Sep - 08 Oct	easyJet
08 Sep - 10 Oct	TAP

Also check the deals for one-way flights from Lisbon 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 Lisbon to Sofia in September from $163

Return flights