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

Return flights

30 Sep - 07 Oct	Air Canada	direct
27 Sep - 30 Sep	Delta
27 Sep - 01 Oct	Delta
27 Sep - 04 Oct	Delta
26 Sep - 30 Sep	Delta
26 Sep - 04 Oct	Delta
27 Sep - 03 Oct	Delta
23 Sep - 30 Sep	Air Canada	direct
24 Sep - 01 Oct	Air Canada	direct
24 Sep - 28 Sep	Air Canada	direct
26 Sep - 03 Oct	Delta
25 Sep - 01 Oct	Delta
27 Sep - 30 Sep	Air Canada	direct
28 Sep - 05 Oct	Air Canada	direct
29 Sep - 06 Oct	Air Canada	direct
16 Sep - 23 Sep	Air Canada	direct
20 Sep - 27 Sep	Air Canada	direct
26 Sep - 28 Sep	Delta
26 Sep - 29 Sep	Delta
24 Sep - 29 Sep	Delta

Also check the deals for one-way flights from Montreal to Chicago 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 Chicago in September from $202

Return flights