He has been with the firm for 16 years, including 13 at the helm.
His replacement has yet to be appointed but CBAM said the search for a successor is “well underway.”
Mr Andrew will remain with CBAM until Spring to help with the transition to a successor.
Adrian Sainsbury, chief executive of parent company Close Brothers, said: “We take a long term view of our businesses and Martin and I have been discussing succession planning in CBAM for some time. I would like to thank him for giving us time to ensure we could plan for a smooth transition.
“Martin has made an enormous contribution to the group during his time here, and I have very much enjoyed working with him. We will miss his strategic thinking and his ideas. Martin has built a high quality business with an excellent team at CBAM and he will leave a significant and lasting legacy behind him.”
The announcement came as Close Brothers released its latest trading statement covering the three months to the end of October.
CBAM benefited from from net inflows that rose 8% on an annualised basis.
CBAM ended the quarter with £17.4bn of assets under management and advice, a slight rise from the £17bn reported at the end of July.
UK Financial Planning forms a key part of CBAM’s growth strategy as the firm looks to expand its regional footprint.
The firm purchased Surrey-based PMN Financial Management LLP, which provides advice mainly to High Net Worth client families, for an undisclosed sum.
The firm took a hit at the start of the Coronavirus when its asset management arm reported a £1bn hit to client assets.
CBAM's growing Financial Planning and wealth management arm employs more than 110 advisers in 10 offices across the UK.
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