Lloyd's director of regulation will leave the Corporation at the end of March to become director of insurance at the Financial Services Authority (FSA).
David Gittings, who has headed the division since 1995, said: "It is a tremendous challenge. I am looking forward to it with some relish. There is a big job to be done."
Responsibility for the individual functions within regulation will now fall to the chief executive and director of finance and operations.
Lloyd's and the FSA will review the arrangements in order to implement plans to modernise the market.
Last month, Lloyd's chairman Sax Riley's working party and management consultancy Bain & Co recommended replacing the regulatory and market boards and committees with a single franchise board.
Under the proposals, Lloyd's will act as a franchisor in the management of the marketplace, with the managing agents as franchisees.