Merry was at financial services business Matrix Group from 2007 until mid-2011 and before that was finance director and CEO at Whitehead Mann. He has also worked at Clifford Chance and PricewaterhoseCooper.
His appointment, with immediate effect, follows a number of board changes announced alongside the company’s trading update on 23 January.
At the time Bob Morton and Andy Raynor stepped down from their positions as chairman and CEO respectively.
Adrian Martin, who was caretaker CEO until a new appointment could be made, will now assume the role of non-executive chairman.
Martin said of the appointment: "Since announcing our trading update on 23 January, one of my priorities has been to identify a new CEO. Chris has a strong track record of transforming businesses and I am confident with his experience, RSM has the leadership to restore profitability and growth."
RSM Tenon said in January that it expected to report revenue in the six months to 31 December 10% lower than in the same period in 2010.
This will in turn lead it to record a pre-tax loss for the period, it predicted, the size of which is still unknown.
