Max Taylor is stepping down as chairman of Lloyd's in December because the council is reverting the role to being a part-time position from January next year.
He will be replaced by his deputy, Sax Riley, the former chairman of Sedgwick, for one year until the new elections.
Taylor, who has held the position for three years, declined to comment on his future plans but said he had been invited by the council to stand for a second term.
He said: "My term ends in December of this year and although the council has invited me to stand for a second term, I want to continue my career in a full-time, executive capacity and so have decided against standing again."
The role of Lloyd's chairman was always part-time, until 1992, when it was converted to full-time to push through the reconstruction and renewal reforms of the 300-year-old market, following the disastrous losses of the late 1980s.
The reversion back to part-time reflects Lloyd's regained confidence in its future.
Nick Prettejohn, chief executive officer of Lloyd's, said: "I shall be sad to see him [Taylor] leave at the end of this year, but I fully understand his decision to move on to fresh challenges."