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

Return flights

01 Dec - 10 Dec	Air Canada
03 Dec - 10 Dec	Air Canada
10 Dec - 16 Dec	Delta
09 Dec - 16 Dec	British Airways
01 Dec - 08 Dec	British Airways
05 Dec - 12 Dec	British Airways
07 Dec - 14 Dec	British Airways
03 Dec - 08 Dec	American Airlines
22 Dec - 17 Jan	Air Canada
15 Dec - 10 Jan	Air Canada
11 Dec - 18 Dec	British Airways
31 Dec - 07 Jan	British Airways
13 Dec - 10 Jan	KLM
30 Dec - 06 Jan	Frontier Airlines
15 Dec - 22 Dec	British Airways
26 Dec - 08 Jan	United
18 Dec - 10 Jan	Air France
12 Dec - 03 Jan	Frontier Airlines
25 Dec - 01 Jan	British Airways
23 Dec - 02 Jan	Air Canada

Also check the deals for one-way flights from St. Louis 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 St. Louis to London in December from $622

Return flights