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

Return flights

07 Oct - 21 Oct	Turkish Airlines
02 Oct - 16 Oct	Turkish Airlines
28 Oct - 04 Nov	United
29 Oct - 05 Nov	United
31 Oct - 07 Nov	United
26 Oct - 02 Nov	United
10 Oct - 25 Oct	TAP
25 Oct - 01 Nov	United
13 Oct - 20 Oct	United
19 Oct - 26 Oct	United
22 Oct - 29 Oct	United
08 Oct - 15 Oct	United
20 Oct - 27 Oct	United
14 Oct - 21 Oct	United
07 Oct - 14 Oct	United

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 461€

Return flights