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

Return flights

15 Sep - 22 Sep	WestJet
08 Sep - 27 Sep	Air Transat
08 Sep - 25 Sep	Air Transat
08 Sep - 20 Sep	Air Transat
17 Sep - 27 Sep	WestJet
18 Sep - 27 Sep	WestJet
14 Sep - 21 Sep	WestJet
21 Sep - 30 Sep	Air Transat
22 Sep - 01 Oct	Air Transat
24 Sep - 29 Sep	Air Transat
23 Sep - 29 Sep	Air Transat
25 Sep - 01 Oct	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 $732

Return flights