British Airways said it will shift its Texas flights to London's Heathrow Airport from the British capital's Gatwick Airport in March.
The shift includes one daily flight between London and Dallas and two daily flights between London and Houston.
The change is being made under the "Open Skies" accord between the U.S. and European Union, which freed airlines to fly from any U.S. or European city.
"Today's announcement is a major step resulting from the open skies agreement," said Willie Walsh, British Airways' chief executive, in a conference call with reporters.
Walsh said the 224-seat Boeing 777s British Airways flies between London and Dallas are typically about 70% full, but that the move to Heathrow will to change that.
"We would expect that transferring this to Heathrow, we would see a significant increase," Walsh said.
The airline is also considering other U.S. route changes under Open Skies, Walsh said.