The appointments follow the arrival of experienced industry professional and diversity campaigner Dame Helena Morrissey as a non-executive director at he beginning of this year.
The new non-executive directors are Emma Griffin and Lesley-Ann Nash who will join the board with effect from 5 February and 1 June respectively.
The additions mean that four of the company's seven non-executive directors are women.
Emma Griffin is currently a non-executive director and chair of the investment committee of Industrial Alliance Financial Group, one of Canada's largest insurance and wealth management companies and a non-executive director of the private investment company Claridge.
She was a founding partner of the stockbroking firm Oriel Securities. In her early career she worked at HSBC James Capel and Schroders.
Lesley-Ann Nash is stepping down from her position as a director in the Government’s Cabinet Office, where she spent six years leading large scale commercial and consumer programmes.
Prior to that she was a managing director at Morgan Stanley from 1998-2009, having previously worked at UBS and Midland Bank. She is a Fellow of the Chartered Institute of Management Accountants (CIMA) and a trustee of the North London Hospice.
Iain Cornish, chair of St James's Place, said: "Both Emma and Lesley-Ann have substantial experience at a senior level across a number of sectors and I am delighted that they have both agreed to join the board.
“The new perspectives and insights they bring will undoubtedly add further value to the Board and I look forward to working with them."
Following her appointment to the board Ms Emma Griffin will also be appointed as chair of the Board of St James's Place Unit Trust Group Limited.
Dame Helena stepped down recently from her role as head of personal investing at Legal & General Investment Management after two years in the role. Before L&G she was chief executive of Newton Investment Management from 2001 to 2016, a company she joined in 1984.
SJP has also recently been under fire, particularly from national media, for its charges and sales incentives for staff. Newspaper reports suggest the firm will cut down on staff incentives and perks in future.
The rapidly-growing company has 4,300 advisers and is among the largest wealth managers in the UK. It is currently recruiting at the rate of 100 new advisers a month.