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

Return flights

01 Dec - 06 Dec	Icelandair
08 Dec - 15 Dec	Icelandair
08 Dec - 21 Dec	Icelandair
22 Dec - 01 Jan	Air Canada
14 Dec - 21 Dec	United
15 Dec - 28 Dec	Air Canada
26 Dec - 02 Jan	Air Canada
21 Dec - 29 Dec	Air Canada
21 Dec - 04 Jan	Air Canada
21 Dec - 28 Dec	Air Canada
18 Dec - 25 Dec	United
14 Dec - 21 Dec	British Airways	direct
19 Dec - 28 Dec	Air Canada
28 Dec - 04 Jan	British Airways	direct
21 Dec - 05 Jan	United
18 Dec - 02 Jan	United
26 Dec - 02 Jan	British Airways	direct
21 Dec - 04 Jan	British Airways	direct
21 Dec - 05 Jan	British Airways	direct

Also check the deals for one-way flights from Portland 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 Portland to London in December from $503

Return flights