The Prime Minister put the picture – taken by French president Emmanuel Macron at a dinner at London’s V&A Museum on Thursday night – on the social media site yesterday.
The leaders were surrounded by Franco-British Council members, recreating a famous selfie taken by Hollywood stars at the 2014 Oscars.
The stars’ selfie included Brad Pitt, Angelina Jolie and Ellen DeGeneres, with disgraced actor Kevin Spacey in the background.
Mrs May captioned the picture: “More than a century on from the “entente cordiale” let us celebrate our own ‘entente chaleureuse’.”
The entente cordiale, signed in 1904, paved the way for the modern relationship between both countries.
Entente chaleureuse means “warm agreement”.
The Franco-British Council dinner, attended by guests from the worlds of culture, sport, business and science, followed the announcement of new UK-France co-operation at Calais, including an extra £44million from Britain for security on the French side of the Channel.