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

Return flights

19 Sep - 11 Oct	FrenchBee
15 Sep - 30 Sep	FrenchBee
08 Sep - 11 Sep	FrenchBee
29 Sep - 06 Oct	FrenchBee
16 Sep - 22 Oct	Condor
30 Sep - 07 Oct	Porter Airlines (Canada) Ltd
08 Sep - 15 Sep	FrenchBee
26 Sep - 03 Oct	FrenchBee
15 Sep - 22 Sep	FrenchBee
10 Sep - 17 Sep	FrenchBee
23 Sep - 05 Oct	Porter Airlines (Canada) Ltd
19 Sep - 26 Sep	FrenchBee
28 Sep - 05 Oct	FrenchBee
17 Sep - 24 Sep	FrenchBee
14 Sep - 21 Sep	FrenchBee
21 Sep - 28 Sep	FrenchBee
23 Sep - 30 Sep	Air Transat
24 Sep - 01 Oct	FrenchBee
28 Sep - 18 Oct	FrenchBee
27 Sep - 04 Oct	Air Transat

Also check the deals for one-way flights from Montreal 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 Montreal to Sofia in September from 546€

Return flights