Nick Sinfield departs are three years in the role
Catlin has appointed its US underwriting hub chief executive Andrew McMellin as its next London chief executive.
McMellin will replace Nick Sinfield, who is leaving the company after 11 years.
The London hub wrote more than $2.4bn (£1.4bn) of premiums last year.
Group chief operating officer Paul Jardine will serve as interim CEO until McMellin takes up the post in the first half of next year.
Catlin group chief executive Stephen Catlin said: “Andrew has done a superb job of managing the profitable growth of our US-based operations over the past two years and will continue in this role for several months to assure a smooth transition.
“He will then be responsible for all activities carried out by our London-based operations, which produced more than US$2.4 billion in gross premiums written in 2013.”
Sinfield had been the CEO of Catlin’s London operating hub since November 2011 and joined the insurer in 2003 as group claims director.
Catlin said: “I would like to thank Nick Sinfield for his many achievements during his more than a decade of service with Catlin. Nick is largely responsible for the development of Catlin’s world-class claims team and has made significant contributions during the past three years as CEO of the London hub. I wish Nick all the best in his future endeavours.”