Prakesh joined the group in September 2020 as chief technology officer, following the merger of Tilney and Smith and Williamson.
He provides the role with previous experience as both chief consumer digital and information officer at Centrica, and chief digital and information officer at the UK department of work and pensions.
Prakesh has also been named as deputy president of the BCS, the chartered institute for IT, earlier this month.
Chris Woodhouse, chief executive at Tilney Smith and Williamson, said: “Mayank has an impressive track record leading teams and implementing large-scale transformation programmes across the private and public sector.
“As the new chief operations officer, Mayank will continue to drive our digital investment and innovation agenda forward alongside leading our operations teams to deliver excellent client experience and support the scalability of our fast-growing business.”
Effective from 1 April 2021, Prakash will replace the retiring Donald Reid, who will take on a part-time advisory role following his 11 years at the firm.
Woodhouse added: “Donald has made a huge contribution to the business over the last eleven years, which has been a period of significant growth and change.
“We wish Donald well for his retirement and are delighted that we will continue to have access to his counsel in his new advisory role.”