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

Return flights

06 Oct - 17 Oct	Delta
06 Oct - 12 Nov	KLM
09 Oct - 25 Oct	Delta
02 Oct - 06 Oct	Delta
03 Oct - 10 Oct	Delta
02 Oct - 05 Oct	Delta
11 Oct - 17 Oct	Delta
28 Oct - 01 Nov	Delta
17 Oct - 26 Oct	Air Transat
03 Oct - 06 Oct	Virgin Atlantic
10 Oct - 19 Oct	Virgin Atlantic
03 Oct - 13 Oct	KLM

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

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 October from $659

Return flights