AirHint found the following cheapest return flights from Ottawa (YOW) to London (LGW) in September 2025 (see full year).

Return flights

17 Sep - 25 Sep	WestJet
17 Sep - 20 Sep	WestJet
23 Sep - 30 Sep	WestJet
10 Sep - 25 Sep	WestJet
19 Sep - 23 Sep	Air Transat
19 Sep - 22 Sep	Air Transat
07 Sep - 22 Sep	Air Transat
20 Sep - 27 Sep	WestJet
24 Sep - 01 Oct	Air Transat
03 Sep - 10 Sep	Porter Airlines (Canada) Ltd
26 Sep - 02 Oct	Air Transat
20 Sep - 22 Sep	Air Transat

Also check the deals for one-way flights from Ottawa 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 Ottawa to London in September from $664

Return flights