The former chairman of St James's Place will lead the board of Richard Buxton's investment management business.
Sarah Bates will now join Merian Global Investors as a non-executive director and chairman after retiring from SJP earlier this year.
She had been chairman of the FTSE 100 wealth manager since 2014.
Meanwhile Mark Gregory, the former chief financial officer at Legal & General, will also join the business as a non-executive director.
Mr Buxton, chief executive of Merian Global Investors and manager of the firm’s UK Alpha fund said: "Merian Global Investors is in the early stages of life as an independent asset management business and I’m thrilled that Sarah Bates and Mark Gregory are joining our board at this pivotal time.
"I'm a great believer in the power of independent directors to drive positive change and I have every confidence that Sarah and Mark’s considerable experience will be a significant asset to our business as we grow."
Merian is owned by Mr Buxton and five other fund managers - Ian Heslop, Dan Nickols, Richard Watts, and Amadeo Alentorn - after the business demerged from OId Mutual with the backing of private equity firm TA Associates.