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

Return flights

12 Aug - 26 Aug	Air Canada
12 Aug - 21 Aug	Finnair
12 Aug - 26 Aug	British Airways	direct
10 Aug - 25 Aug	British Airways	direct
05 Aug - 29 Aug	Air Canada
26 Aug - 05 Sep	United
11 Aug - 05 Sep	United
05 Aug - 29 Aug	Finnair	direct
11 Aug - 05 Sep	British Airways	direct
19 Aug - 01 Sep	Aer Lingus
26 Aug - 05 Sep	British Airways	direct
15 Aug - 05 Sep	British Airways	direct

Also check the deals for one-way flights from Seattle 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.

Book a cheap hotel in London

Cheap car rent in London

Cheapest return flights from Seattle to London in August from 493€

Return flights