The cheapest London to Hanoi return flight on the radar right now is £450, flying with Hainan Airlines + China Eastern via one or more connections. It covers departures in September 2026, and every dated link below opens that exact LHR–HAN search on Skyscanner. That is roughly 13% below the £516 this route usually costs. Across 76 recorded checks it has ranged between £385 and £901. Our sampling points to September 2026 as the cheapest month to fly London to Hanoi.
Prices are re-checked against Skyscanner automatically, and every one shows when it was last confirmed, so nothing here is older than it looks. Not flying from London? We track 58 other departure cities for Hanoi, listed at the foot of this page.
Prices like this tend to vanish fast. If it has gone when you look, try the days either side of the dates above, since London to Hanoi is often still worth booking within a day or two of the fare we found.