The airline is offering five weekly flights on the route, which complements its existing service to Narita airport in Japan's capital city.
BA's oneworld alliance partner American Airlines also expanded its presence in the Far East with the launch of a new service linking Tokyo Haneda to New York JFK.
Both inaugural services departed within minutes of one another yesterday morning.
Another oneworld carrier, Japan Airlines, has been operating flights from Tokyo Haneda to Charles de Gaulle airport in Paris since October last year.
Speaking yesterday, Jamie Cassidy, BA's general manager in the Asia Pacific region, said: 'Today is a historic day for British Airways as we start our new route from Haneda, which complements our existing service from Narita.
'The start of this route allows us to offer our customers greater choice and flexibility. We are proud to be the only carrier operating from Haneda direct to the UK.'
He went on to say that the new service demonstrates BA's commitment to Japan and represents a step forward in its relationship with Japan Airlines.