Chelsea chairman Bruce Buck is to step down from his role on 30 June, with co-owner Todd Boehly set to succeed him.
American Buck, 76, who had been chairman since Roman Abramovich became owner in 2003, was set to continue in the role after the takeover of the club by a Boehly-led consortium last month.
A change of direction means he will now support the club as a "senior adviser".
"Now is the right time to step down and let new ownership build on the strong foundations we have in place," he said.
"The owners have a compelling vision for Chelsea's future, and I look forward to helping them achieve it in this new role alongside our incredible staff, players, coaches and supporters.