AirHint found the following cheapest return flights from Ontario (ONT) to London (LHR) in October 2025 (see full year).

Return flights

17 Oct - 25 Oct	Delta
22 Oct - 04 Nov	British Airways
26 Oct - 05 Nov	Iberia
20 Oct - 09 Nov	Iberia
12 Oct - 19 Oct	Iberia
03 Oct - 10 Oct	Iberia
14 Oct - 19 Oct	British Airways
03 Oct - 05 Oct	British Airways
08 Oct - 19 Oct	British Airways
03 Oct - 12 Oct	British Airways
28 Oct - 05 Nov	Avianca
25 Oct - 05 Nov	Avianca
02 Oct - 10 Oct	Avianca
01 Oct - 17 Oct	China Airlines
10 Oct - 12 Oct	British Airways

Also check the deals for one-way flights from Ontario to London in October.

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 Ontario to London in October from $625

Return flights