A British Airways Boeing 777 touched down at Colombo's Bandaranaike International Airport this afternoon, marking the resumption of services, the Ministry of Economic Development said.
The service was suspended in 1998 owing to the island's armed conflict that ended in 2009.
The new thrice-a-week London-Colombo-London sector will service London's Gatwick airport on Sundays, Wednesdays and Fridays.
British Airways said the service would be a boon to British travellers to Sri Lanka.
Over 114,000 British tourists visited Sri Lanka last year, which is second only to Indian tourists.
"Sri Lanka has emerged as one of the most popular destinations among leisure and business travellers from Britain and Europe," Christopher Fordyce, BA's regional manager for South Asia said.