Grimstone, a former investment banker at Schroders, replaces Lord Mervyn Davies of Abersoch whose term expired recently, ADCB said in a statement.
He has also run businesses in London, New York and Asia Pacific and was an official in the UK’s Treasury where he was responsible for privatisation and policy towards state-owned enterprises.
Grimstone will attend board meetings and advise on all aspects of the bank’s business including strategy, the statement added.
The ADCB is the UAE’s third biggest bank by market value, employing over 3,600 people and serving approximately 470,000 retail customers and over 36,000 wholesale clients in 49 branches in the UAE.
It also has two branches in India and one branch in Jersey. Its assets totalled AED182bn as at the end of September.