The cheapest London to Hanoi return flight on the radar right now is £363, flying with China Southern via one or more connections. It covers departures in November 2026, and every dated link below opens that exact LHR–HAN search on Skyscanner. At 29% under the £514 we normally record here, it is one of the strongest LHR–HAN fares in our index. Across 79 recorded checks it has ranged between £357 and £901. Our sampling points to November 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 60 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.