The appointment of Graeme Hardie as the bank's eighth non-executive director comes as the new entrant looks to build up a major branch network.
Metro Bank is understood to be eyeing plans to raise 45 million in fresh capital to enable it to accelerate its expansion plans.
The group, which was the first high street bank to launch in the UK for more than 100 years, originally aimed to have 40 branches by 2014, increasing the number to 200-plus - chiefly within the M25 covering London and the Home Counties - by 2020. But it is thought that it now hopes to accelerate those plans.
Metro Bank chairman Anthony Thomson said Hardie brought with him a "wealth of banking experience" and an "excellent understanding of the regulatory framework".
"We're delighted to have him on board," Thomson said. "Our non-executive directors offer a realm of perspectives and guidance to the Metro Bank board, borne out by strong track records in retail banking."
Hardie's 30-year career in banking has included overseeing the retail branch change programme following Royal Bank of Scotland's takeover of NatWest in 2000. He was subsequently appointed managing director of the bank's 1,700-plus branches.
Hardie then went on to become executive director, retail banking, at Abbey, and was part of the Santander acquisition team.
In September 2008, he was made a non-executive director of Dunfermline Building Society during a boardroom shake-up and jobs cull. The 140-year-old society went on to be acquired by larger rival Nationwide following hefty losses.
Two years ago, Hardie was also hired by the Financial Services Authority to advise on retail markets.
Hardie said yesterday: "Metro Bank has thrown down the gauntlet to the traditional banks, which have often claimed to be taking customer service seriously but not delivered.
"This promises to be an exciting period of change in the UK banking industry. We are witnessing a new era of banking, one that does actually put the customer first, and I'm delighted to be part of it."
The bank's other non-executives include Stuart Bernau, the former retail director at Nationwide, and Ben Gunn, who was life and pensions boss at Friends Provident.
Its executive team is headed by chief executive Craig Donaldson, who was most recently managing director of retail products at Royal Bank of Scotland.
Metro promised to revolutionise the British banking experience when it opened its first branch in Holborn in London in July.
It has since opened a further three branches, which it refers to as stores.
The group is based on the model used for Commerce Bank in the US, which was founded by Vernon Hill - Metro's founder and a non-executive director - in 1973.