"For me, it really is my dream job."
A respected figure in business circles, McLean joined Westpac in 1999 as head of the debt capital markets division in New Zealand.
He became head of Westpac Institutional Bank in 2004 and in 2012 shifted to the United States to become managing director of the lender's New York branch.
His appointment to the top job is a departure from common practice, as Australians have tended to hold the position in the past.
He is the first Kiwi to lead Westpac NZ since Harry Price, who was in the job between 1992 and 1999 and oversaw the merger with Trust Bank.
McLean sees many growth opportunities for the bank in areas such as agribusiness, KiwiSaver, the small and medium-sized business sector and new banking technology.
But he said stiff home-loan competition was squeezing margins.
"New Zealand is in pretty good shape. But the competitive environment from a shareholder's point of view is not that great because it means our margins are under pressure. It's good for consumers."
Westpac NZ reported a 13 per cent rise in annual cash earnings to $864 million last year - largely thanks to a steep decline in bad debts.
McLean said it was not going to be possible to keep growing earnings, to such an extent, on the back of falling levels of loan impairment.
"Therefore we've got to look at the other lines, which are revenue and expenses," he said. "My view is that we should be in a relatively good economy and looking to grow our revenue base by helping customers to achieve their goals."
Massey University banking expert David Tripe said McLean was highly experienced and knew Westpac's business well, although some might question his background being more in wholesale than retail.
Clare, McLean's predecessor, earned a $3.1 million pay packet in the 2013 financial year.
David McLean
• Westpac NZ chief executive.
• 56 years old.
• Joined Westpac in 1999.
• Previous Westpac roles included head of debt capital markets, general manager of private wealth and insurance, head of Westpac Institutional Bank and, most recently, managing director of Westpac's New York branch.
• Also established the New Zealand branch of Deutsche Bank and had stints with NatWest, Deutsche Morgan Grenfell and Southpac/National Bank in the 1980s and 1990s.
• Has a background in law and is a barrister and solicitor of the High Court of New Zealand.