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

Return flights

03 Sep - 14 Sep	WestJet
19 Sep - 24 Sep	WestJet
30 Sep - 09 Oct	WestJet
28 Sep - 13 Oct	WestJet
12 Sep - 17 Sep	WestJet
15 Sep - 24 Sep	WestJet
27 Sep - 13 Oct	WestJet
05 Sep - 10 Sep	WestJet
06 Sep - 25 Sep	WestJet
29 Sep - 20 Oct	WestJet
29 Sep - 11 Oct	WestJet
02 Sep - 12 Sep	WestJet
21 Sep - 05 Oct	WestJet
20 Sep - 05 Oct	WestJet

Also check the deals for one-way flights from Calgary to London 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 London in September from $694

Return flights