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

Return flights

13 Sep - 18 Sep	Air Serbia	direct
27 Sep - 28 Sep	Air Serbia	direct
20 Sep - 21 Sep	Wizz Air
19 Sep - 21 Sep	Air Serbia	direct
20 Sep - 21 Sep	Air Serbia	direct
12 Sep - 18 Sep	Air Serbia	direct
12 Sep - 17 Sep	Air Serbia
04 Sep - 07 Sep	Air Serbia	direct
05 Sep - 12 Sep	Air Serbia	direct
06 Sep - 07 Sep	Air Serbia	direct

Also check the deals for one-way flights from Belgrade 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 Belgrade to Sofia in September from 153€

Return flights