AirHint found the following cheapest return flights from Ontario (ONT) to London (LHR) in May 2026 (see full year).

Return flights

01 May - 06 May	Iberia
04 May - 13 May	British Airways
04 May - 14 May	British Airways
02 May - 18 May	British Airways
03 May - 11 May	British Airways
01 May - 10 May	British Airways
02 May - 09 May	Iberia
14 May - 21 May	Lufthansa
15 May - 22 May	Lufthansa
18 May - 25 May	Lufthansa
25 May - 05 Jun	Iberia
12 May - 12 Jun	Air France
30 May - 17 Jun	Air France
14 May - 04 Jun	British Airways
26 May - 02 Jun	Alaska Airlines
15 May - 03 Jun	jetBlue
15 May - 05 Jun	British Airways
27 May - 06 Jun	Alaska Airlines
26 May - 04 Jun	Alaska Airlines
17 May - 07 Jun	jetBlue

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

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 May from 615€

Return flights