Vietnam Airlines is leaving Gatwick to launch a direct service from Heathrow airport, starting March 31.
The national carrier currently operates two twice-weekly flights to the UK capital, one from Hanoi and the other from Ho Chi Minh, with a B777-200ER.
From July, the airline will use its new fleet of 787-9 Dreamliners to operate five weekly services to Hanoi and Ho Chi Minh City.
Vietnam said this route will be further increased to a daily service, but have not provided dates on when this will happen.
Vietnam Airlines CEO Dr Pham Ngoc Minh said: “Our vision, and that of the government of Vietnam, is for Vietnam Airlines to become the major carrier in Southeast Asia – and this move represents a tremendous step forwards in achieving that goal.”
Heathrow CEO John Holland-Kaye said: “We are delighted that Vietnam Airlines has chosen to operate its new Dreamliner 787 fleet from Heathrow, securing regular direct flights from the UK to a vital emerging market.
“This demonstrates once again that only a strong hub airport like Heathrow, with a mix of premium direct and transfer passengers, can help Britain win the race for growth,” he added.
Vietnam Airlines launched the first direct, nonstop flights between London and Hanoi and Ho Chi Minh City in 2011.
The lack of capacity at Heathrow meant the agreement between the airport and Vietnam Airlines took seven years to complete. There are currently 30 airlines waiting for slots.