AirHint found the following cheapest one-way flights from Chicago (MDW) to Montreal (YUL) in September 2025 (see full year).

One-Way flights

25 Sep	Porter Airlines (Canada) Ltd
15 Sep	Porter Airlines (Canada) Ltd
17 Sep	Porter Airlines (Canada) Ltd
10 Sep	Porter Airlines (Canada) Ltd
19 Sep	Porter Airlines (Canada) Ltd
06 Sep	Porter Airlines (Canada) Ltd
03 Sep	Porter Airlines (Canada) Ltd
04 Sep	Porter Airlines (Canada) Ltd
05 Sep	Porter Airlines (Canada) Ltd
07 Sep	Porter Airlines (Canada) Ltd

Also check the deals for return flights from Chicago to Montreal 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 one-way flights from Chicago to Montreal in September from 38€

One-Way flights