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

Return flights

01 Dec - 11 Dec	KLM
08 Dec - 15 Dec	Delta
05 Dec - 16 Dec	Delta
01 Dec - 08 Dec	Air France
15 Dec - 23 Dec	Air France
06 Dec - 14 Dec	Air France
11 Dec - 15 Dec	Delta
12 Dec - 19 Dec	Air France
16 Dec - 23 Dec	Air France
16 Dec - 07 Jan	Virgin Atlantic
12 Dec - 21 Dec	Air France
11 Dec - 10 Jan	Virgin Atlantic
15 Dec - 10 Jan	Virgin Atlantic
24 Dec - 08 Jan	Delta
27 Dec - 17 Jan	Virgin Atlantic
26 Dec - 17 Jan	Virgin Atlantic
28 Dec - 11 Jan	Air France
18 Dec - 11 Jan	KLM
26 Dec - 01 Jan	Delta
28 Dec - 05 Jan	KLM

Also check the deals for one-way flights from Chicago 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 Chicago to London in December from 444€

Return flights