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

Return flights

28 Jul - 07 Aug	Icelandair
31 Jul - 03 Aug	Icelandair
20 Jul - 06 Aug	Icelandair
23 Jul - 06 Aug	Icelandair
29 Jul - 03 Aug	Icelandair
28 Jul - 03 Aug	Icelandair
29 Jul - 07 Aug	Icelandair
24 Jul - 04 Aug	Icelandair
17 Jul - 03 Aug	Icelandair
30 Jul - 04 Aug	Icelandair
16 Jul - 23 Jul	Icelandair
20 Jul - 27 Jul	Icelandair
17 Jul - 28 Jul	Icelandair
19 Jul - 24 Jul	jetBlue
17 Jul - 26 Jul	Icelandair
18 Jul - 26 Jul	Icelandair
17 Jul - 20 Jul	Icelandair
07 Jul - 18 Jul	Air Canada
16 Jul - 20 Jul	Icelandair
16 Jul - 24 Jul	Virgin Atlantic

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 452€

Return flights