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

Return flights

30 Dec - 10 Jan	British Airways
05 Dec - 20 Dec	Iberia
02 Dec - 16 Dec	British Airways
13 Dec - 20 Dec	Iberia
01 Dec - 10 Dec	Iberia
23 Dec - 13 Jan	British Airways
01 Dec - 08 Dec	Iberia
26 Dec - 07 Jan	British Airways
29 Dec - 11 Jan	Iberia
13 Dec - 02 Jan	Air Canada
22 Dec - 11 Jan	Iberia
23 Dec - 09 Jan	Iberia
23 Dec - 08 Jan	British Airways
26 Dec - 14 Jan	Iberia
08 Dec - 12 Dec	Iberia
19 Dec - 17 Jan	British Airways
19 Dec - 28 Dec	British Airways
18 Dec - 29 Dec	Iberia
20 Dec - 28 Dec	Iberia
23 Dec - 31 Dec	Avianca

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

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 December from $763

Return flights