The carrier, which plans to offer 22 flights per day from the London airport to the US by summer 2022, marked the arrival of its first flight into Heathrow on Friday (15 April).
United employees and crew joined Bob Schumacher, director of sales UK and Ireland, to welcome United Flight 24 from Boston.
The new service will be operated with Boeing 767-300 aircraft, which feature a total of 167 seats – 46 flat-bed seats in business class, 22 United Premium Plus seats and 99 in economy.