The banking giant said Grimstone – who has been chairman of Edinburgh-based life and pensions group Standard Life since may 2007 – will take up his post on 1 January 1.
He succeeds Sir Michael Rake, who will step down in December after eight years in the role. Grimstone will also become senior independent director at Barclays.
The move is the latest change at the top of the banking giant, which last month confirmed former JP Morgan banker Jes Staley as its new chief executive, replacing Antony Jenkins, in a move that analysts said signals a bid to return the lender to its previous investment banking glory days.
Grimstone, who will continue in his role as Standard Life chairman, previously spent 13 years with financial group Schroders in London, Hong Kong and New York, and was vice-chairman of Schroders’ worldwide investment banking activities.
He has also worked for a range financial firms around the world, and is currently an adviser to the Abu Dhabi Commercial Bank, which is one of the largest commercial banks in Abu Dhabi. He has also worked in various posts for the Department of Health and the Treasury.
Barclays chairman John McFarlane said: “I am delighted that Sir Gerry Grimstone has accepted the board’s invitation to join Barclays and to become deputy chairman and senior independent director.
“Sir Gerry commands great respect within the financial services industry and will bring immense experience, integrity and knowledge to the role.”
The Barclays board ousted previous chief executive Jenkins, who came from a retail banking background, in July for lacklustre revenue growth and a flat share performance. He was appointed in 2012 in the aftermath of the Libor rate-fixing scandal, and toned down the investment banking side of the business.
Grimstone said: “I am immensely looking forward to joining the Barclays boards and to playing my part in delivering Barclays’ strategic priorities.
“I am particularly looking forward to supporting John McFarlane and Jes Staley as they seek to complete the cultural transformation of Barclays and accelerate the delivery of sustainable shareholder returns.”
Outgoing deputy chairman Rake said: “The last eight years have been an eventful and difficult period for the banking industry. However, Barclays is emerging in a stronger position and I am very confident that it will succeed and prosper under its new leadership.”