Sanlam Private Investments UK chair Daniël Kriel is stepping down after nearly six years in the role.
He will be replaced by Sanlam UK chief executive Jonathan Polin.
Polin became chief executive of the Sanlam UK group in January 2016.
Kriel is also stepping down as Sanlam Private Wealth chief executive after 13 years.
Sanlam says the process to appoint a new chief executive officer for that business is underway.
Group chief executive Robert Roux has assumed executive responsibility in the interim, working with the Sanlam Private Wealth executive team to ensure a smooth transition.
Kriel will remain available to the business until the end of November to provide support where necessary.
Kriel joined the Sanlam Group in 1998, and was responsible for marketing, institutional sales and retail distribution at Sanlam Investment Management.
In March 2005 he was appointed the chief executive of Sanlam Private Investments and he became chairman in November 2012.
South African-listed Sanlam is working to build a bigger advice presence in the UK and in 2016 restructured its business to house Sanlam Private Wealth and Sanlam Wealth Planning under a new division, Sanlam Partners.
Last month, Sanlam UK revealed ambitious plans to grow to 1,000 advisers over the next two years.
Speaking at the Money Marketing Interactive conference last month, Polin said the wealth manager is also planning to invest directly into stocks and bonds in an attempt to cut costs.