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

Return flights

22 Sep - 23 Sep	WestJet	direct
24 Sep - 28 Sep	WestJet	direct
11 Sep - 18 Sep	WestJet	direct
03 Sep - 24 Sep	WestJet	direct
08 Sep - 22 Sep	WestJet	direct
18 Sep - 20 Sep	WestJet	direct
17 Sep - 28 Sep	WestJet	direct
11 Sep - 14 Sep	WestJet	direct
06 Sep - 14 Sep	WestJet	direct
14 Sep - 19 Sep	WestJet	direct
24 Sep - 13 Oct	WestJet
24 Sep - 13 Oct	WestJet	direct

Also check the deals for one-way flights from Calgary 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 Calgary to Chicago in September from 119€

Return flights