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

Return flights

10 Dec - 16 Dec	Icelandair
02 Dec - 09 Dec	Icelandair
12 Dec - 15 Jan	Frontier Airlines
09 Dec - 13 Dec	Aer Lingus
15 Dec - 22 Dec	Aer Lingus
03 Dec - 10 Dec	Icelandair
03 Dec - 09 Dec	Icelandair
08 Dec - 10 Dec	Aer Lingus
13 Dec - 19 Jan	Frontier Airlines
15 Dec - 15 Jan	Aer Lingus
10 Dec - 14 Dec	Aer Lingus
07 Dec - 16 Dec	Aer Lingus
01 Dec - 10 Dec	Icelandair
15 Dec - 20 Jan	Icelandair
08 Dec - 08 Jan	Icelandair
09 Dec - 08 Jan	Icelandair
13 Dec - 21 Jan	Frontier Airlines
31 Dec - 13 Jan	Icelandair
29 Dec - 12 Jan	Icelandair
30 Dec - 11 Jan	Aer Lingus

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 447€

Return flights