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

Return flights

30 Sep - 25 Oct	Lufthansa
11 Sep - 04 Oct	Air Canada
10 Sep - 02 Oct	Air Canada
24 Sep - 08 Oct	Air Canada
08 Sep - 04 Oct	Air Canada
17 Sep - 04 Oct	Lufthansa
27 Sep - 04 Oct	WestJet
10 Sep - 02 Oct	Lufthansa	direct
18 Sep - 05 Oct	Lufthansa
22 Sep - 18 Oct	Air Canada
10 Sep - 17 Sep	WestJet
18 Sep - 22 Sep	Air Canada
11 Sep - 15 Sep	Air Canada
15 Sep - 29 Sep	Lufthansa
08 Sep - 22 Sep	Air Canada
10 Sep - 17 Sep	Lufthansa	direct
15 Sep - 28 Sep	Lufthansa
07 Sep - 27 Sep	Air Canada
04 Sep - 27 Sep	Air Canada
05 Sep - 27 Sep	Air Canada

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.

Book a cheap hotel in London

Cheap car rent in London

Cheapest return flights from Ottawa to London in September from $637

Return flights