Childs, currently non-executive chairman of Hiscox, will take up the position immediately, Lloyd's said in a statement.
He will be one of three deputy chairmen, Lloyd's added.
Childs "has a keen understanding of the challenges the market faces, but also of its strengths and what Lloyd’s can do to help it thrive and be successful," Lloyd's chairman Bruce Carnegie-Brown said.
(Reporting by Carolyn Cohn; editing by Maiya Keidan)