AirHint found the following cheapest return flights from Seattle (SEA) to London (LGW) in April 2026 (see full year).

Return flights

17 Apr - 19 Apr	Icelandair
19 Apr - 27 Apr	Icelandair
07 Apr - 05 May	Icelandair
25 Apr - 03 May	Icelandair
22 Apr - 29 Apr	Icelandair
14 Apr - 22 Apr	Icelandair
14 Apr - 23 Apr	Icelandair
17 Apr - 27 Apr	Icelandair
24 Apr - 30 Apr	Icelandair
23 Apr - 27 Apr	Icelandair
29 Apr - 15 May	Icelandair
28 Apr - 14 May	Icelandair
24 Apr - 03 May	Icelandair
01 Apr - 08 Apr	Icelandair
25 Apr - 09 May	Icelandair
23 Apr - 26 May	Icelandair
06 Apr - 13 Apr	Icelandair

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

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.

Book a cheap hotel in London

Cheap car rent in London

Cheapest return flights from Seattle to London in April from 398€

Return flights