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

Return flights

22 Sep - 14 Oct	Lufthansa
22 Sep - 15 Oct	Lufthansa
22 Sep - 16 Oct	Lufthansa
23 Sep - 16 Oct	Lufthansa
09 Sep - 16 Sep	Lufthansa
10 Sep - 15 Sep	Air Canada
07 Sep - 15 Sep	Air Canada
08 Sep - 15 Sep	Air Canada
06 Sep - 18 Sep	Air Canada
03 Sep - 20 Sep	Icelandair
13 Sep - 21 Sep	Icelandair
11 Sep - 28 Sep	Icelandair
12 Sep - 17 Sep	Icelandair
24 Sep - 29 Sep	Virgin Atlantic
30 Sep - 07 Oct	Icelandair
23 Sep - 16 Oct	Iberia	direct
24 Sep - 01 Oct	British Airways	direct
01 Sep - 01 Oct	Delta
01 Sep - 01 Oct	British Airways	direct
14 Sep - 21 Oct	Delta

Also check the deals for one-way flights from Chicago to London in September.

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 September from 403€

Return flights