Lord Rothermere will become CEO and chairman of Daily Mail and General Trust (DMGT) as Paul Zwillenberg steps down on 30 September.
Last year Lord Rothermere won shareholder approval (63%) to take the Daily Mail, The Mail On Sunday and MailOnline, private.
DMGT was previously listed on the London Stock Exchange since 1932 and is now delisted, a deal estimated to be worth around £2.4bn.
Zwillenberg will leave his board position but will remain as “a senior adviser” to Rothermere.