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

Return flights

14 Aug - 24 Aug	TAP
10 Aug - 30 Aug	TAP
25 Aug - 01 Sep	TAP
27 Aug - 03 Sep	Icelandair
21 Aug - 27 Aug	TAP
15 Aug - 01 Sep	Icelandair
14 Aug - 02 Sep	Icelandair
26 Aug - 01 Sep	Icelandair
31 Aug - 05 Sep	Icelandair
20 Aug - 25 Aug	Icelandair
22 Aug - 31 Aug	TAP
21 Aug - 24 Aug	TAP
07 Aug - 31 Aug	TAP
11 Aug - 25 Aug	TAP
07 Aug - 30 Aug	TAP
04 Aug - 17 Sep	TAP
21 Aug - 07 Sep	TAP
14 Aug - 10 Sep	TAP
07 Aug - 29 Aug	TAP
06 Aug - 17 Sep	Icelandair

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

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 August from 461€

Return flights