Rosier, a veteran with a City career spanning almost 40 years, takes up the role on 1 September.
He previously worked as a senior adviser at Tilney Investment Management Services and prior to that, was a partner at Thurleigh Investment Managers, a wealth management boutique he founded in 2003.
Rosier’s career has also seen him work as a director of SG Warburg where he spent eight years as a UK fund manager and head of UK institutional sales before heading up Warburg Investment Management’s private client business.
He then became a founding director at Mercury Asset Management before it was taken over by Merrill Lynch Investment Managers in 1997. At MLIM he became chairman of private investors and sat on the investment committee.
Rosier is a commissioner of the Royal Hospital Chelsea and chairs the advisory board for the Armed Forces Common Investment Fund. He is a trustee of the Nuffield Trust for the Forces of the Crown and the Battle of Britain Memorial Trust.
Andrew Fleming, chief executive at Waverton, said the firm’s board and shareholders were “delighted” to appoint someone with such an “illustrious career”.
He added: “His industry knowledge and experience across private clients, charities and fund businesses will, I am sure, be an invaluable addition to our organisation which is looking into 2018 with a sense of optimism.”
The hire follows the appointment of former head of investment strategy at Coal Pension Trustees, William Dinning, as a head of investment strategy and communications.