Andrew Beazley becomes deputy chairman.
Beazley has appointed chief executive Andrew Beazley to deputy chairman of the group.
He will be succeeded by group finance director, Andrew Horton. In a statement, the company said a replacement for Horton would be made in due course.
The changes will take effect from 1 September.
In a realted development Johnny Rowell, Executive Director of Beazley Group plc, will be leaving the company.
Andrew Beazley said: "I have every confidence in Andrew Horton as my successor and believe he is the best person to lead the company going forward.
"Andrew is exceptionally well placed to undertake the role, having extensive financial services experience and having been actively involved in the successful management of the business since joining the Group as Finance Director in 2003."
"I look forward to working with Andrew Horton and the rest of the management team in my new role as Deputy Chairman."
Horton added: "I am excited by the challenges ahead as we look to build on Beazley's success and continue to grow and develop the business in new markets."