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

Return flights

21 Sep - 31 Oct	China Eastern
04 Sep - 11 Sep	Air France
04 Sep - 08 Sep	Air France
20 Sep - 23 Sep	LOT
17 Sep - 24 Sep	LOT
24 Sep - 11 Oct	China Southern
25 Sep - 05 Oct	Air France
29 Sep - 14 Oct	Eastar Jet
14 Sep - 17 Sep	Emirates
09 Sep - 16 Sep	Air France
02 Sep - 25 Sep	KLM
19 Sep - 23 Sep	Air France
12 Sep - 19 Sep	Air France
27 Sep - 30 Sep	LOT

Also check the deals for one-way flights from Seoul 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 Seoul to Sofia in September from $691

Return flights