AirHint found the following cheapest return flights from Chicago (MDW) to Sofia (SOF) in October 2025 (see full year).

Return flights

20 Oct - 07 Nov	Frontier Airlines
07 Oct - 21 Oct	Frontier Airlines
12 Oct - 26 Oct	Frontier Airlines
18 Oct - 27 Oct	Frontier Airlines
10 Oct - 30 Oct	Frontier Airlines
01 Oct - 04 Oct	Porter Airlines (Canada) Ltd
15 Oct - 07 Nov	Air France
27 Oct - 27 Nov	Air France
08 Oct - 22 Oct	Air France
07 Oct - 25 Oct	Air France
12 Oct - 02 Nov	Air France
11 Oct - 03 Nov	Air France
03 Oct - 22 Oct	Air France

Also check the deals for one-way flights from Chicago to Sofia in October.

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 Chicago to Sofia in October from $556

Return flights