The ex-Conservative MP will join the trustees as of September 1 this year and will succeed Sir Richard Lambert as chairman on October 4 after the board approved his appointment unanimously, the museum said.
Mr Osborne, who stepped down as editor-in-chief of the Evening Standard newspaper at the end of March, also became a partner at investment bank Robey Warshaw in April and remains chairman of the Northern Powerhouse Partnership.
All my life I have loved the British Museum. To my mind, it is quite simply the greatest museum in the world
He said: “I am absolutely thrilled to be joining the team at the British Museum – and so honoured to have had the opportunity to apply for this role, and to have been chosen by the trustees to become their chair.
“All my life I have loved the British Museum. To my mind, it is quite simply the greatest museum in the world. It’s a place that brings cultures together and tells the story of our common humanity.”
In 2016 Mr Osborne sparked controversy by joking that former Greek finance minister Yanis Varoufakis and then-shadow chancellor John McDonnell both “lost their marbles” in reference to the controversial Elgin Marbles on display at the British Museum, which Greece has long demanded to be returned.
Baroness Minouche Shafik, deputy chair of the British Museum, said Mr Osborne would be working with the board to expand the institution’s audience as it embarked on a “major programme of renewal”.
The British Museum, Tate Modern, the National Gallery and the Victoria and Albert Museum (V&A) all saw an average 78% drop in attendance in 2020 compared with 2019, according to a survey by The Art Newspaper.
Hartwig Fischer, the director of the British Museum, said the museum was undergoing the “biggest transformative project” in its history.
He added: “George Osborne knows the museum well and values the trust the museum enjoys around the world.
“He understands the active role the British Museum is playing in the recovery of the country, creating opportunities for everyone to discover the collection as their own – onsite, through loans to their local museums and online.”