Alistair Darby, who is currently chief operating officer at Marston's, will take up the top job at M&B in October.
He will become M&B's first permanent chief executive since Adam Fowle resigned back in March 2011.
M&G owns the All Bar One, Harvester, Toby Carvery and O'Neills chains, with more than 1,500 outlets overall.
Mr Alistair Darby will take over the chief executive role from Bob Ivell who has been combining it with his position as chairman on a stand-in basis since October of last year.
Mr Ivell said the appointment of Mr Darby had followed an "extensive and rigorous" search process.
He added: "I am confident that we have secured the right person for the role and that drawing on his wealth of operational and brand experience."
Pub and restaurant group Mitchells & Butlers (M&B) has appointed the director of a rival company as its new chief executive.