AirHint found the following cheapest return flights from Seattle (SEA) to London (LGW) in July 2025 (see full year).

Return flights

26 Jul - 28 Aug	Alaska Airlines
28 Jul - 13 Aug	Icelandair
31 Jul - 17 Aug	Spirit Airlines
08 Jul - 16 Jul	Icelandair
22 Jul - 31 Jul	Icelandair
21 Jul - 05 Aug	Scandinavian Airlines
06 Jul - 13 Jul	Scandinavian Airlines
20 Jul - 27 Jul	Icelandair
01 Jul - 09 Jul	Alaska Airlines
02 Jul - 09 Jul	Scandinavian Airlines
25 Jul - 03 Aug	Icelandair
19 Jul - 29 Jul	Icelandair
14 Jul - 21 Jul	jetBlue
25 Jul - 02 Aug	Icelandair
17 Jul - 24 Jul	Icelandair
14 Jul - 28 Jul	Icelandair
31 Jul - 03 Aug	Icelandair
17 Jul - 03 Aug	Icelandair

Also check the deals for one-way flights from Seattle to London in July.

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 Seattle to London in July from $623

Return flights