Ivan Gazidis has left his role as Arsenal chief executive to join Italian club AC Milan.
The 53-year-old, who helped appoint Unai Emery in May as Arsene Wenger’s successor as manager, will begin his new role on 31 October.
Gazidis said that the decision to leave after 10 years at the Gunners was “the hardest of my life”.
“Change and succession is not only inevitable for a club like Arsenal – it is necessary,” he said.
Raul Sanllehi, who was head of football relations at Arsenal has been appointed head of football, and Vinai Venkatesham moves from chief commercial officer to managing director.