The London-based discretionary fund and wealth management service has appointed Andrew Butcher to the role.
He joins the firm from Charles Stanley and Co where he was also chief operating officer.
Current chief operating officer Paul Chavasse will be leaving the firm early next year.
Mr Chavasse was also Rathbones’ head of investment management.
Mr Butcher has 25 years experience in the financial services industry and is chairman of the Tax Incentivised Savings Association Savings and Investment Council.
Rathbones chief executive Andy Pomfret, said: “As Rathbones continues to grow to meet the needs of an increasing number of clients, Andrew’s skills and experience will be essential to maintaining our high quality of investment management services.
“We are delighted to welcome Andrew to the company and look forward to working with him in the future.”
Outside of his work in finance Mr Butcher enjoys mountain climbing and in October he flew to Nepal to complete a trek to the base camp of Mount Everest, raising £27,500 for disadvantaged children.