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

Return flights

03 Dec - 10 Dec	Austrian Airlines
30 Dec - 30 Jan	Lufthansa
12 Dec - 17 Dec	United
13 Dec - 10 Jan	Virgin Atlantic
05 Dec - 27 Dec	Lufthansa
30 Dec - 06 Jan	Lufthansa
13 Dec - 29 Dec	Austrian Airlines
14 Dec - 21 Dec	United
25 Dec - 01 Jan	Air Canada
18 Dec - 10 Jan	KLM
19 Dec - 06 Jan	Frontier Airlines
22 Dec - 30 Dec	Delta
23 Dec - 02 Jan	Frontier Airlines
15 Dec - 02 Jan	Frontier Airlines
26 Dec - 02 Jan	Frontier Airlines
13 Dec - 02 Jan	British Airways
20 Dec - 30 Dec	Lufthansa

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 520€

Return flights