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

Return flights

23 Sep - 30 Sep	Air Serbia
20 Sep - 22 Sep	Air Serbia	direct
20 Sep - 23 Sep	Air Serbia
23 Sep - 30 Sep	Air Serbia	direct
18 Sep - 21 Sep	Air Serbia	direct
18 Sep - 20 Sep	Air Serbia	direct
21 Sep - 25 Sep	Air Serbia	direct
17 Sep - 19 Sep	Wizz Air
19 Sep - 22 Sep	Ryanair
12 Sep - 19 Sep	Ryanair

Also check the deals for one-way flights from Sofia to Belgrade 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 Sofia to Belgrade in September from 140€

Return flights