New Zealand's strong economy - as well as good deposit and lending growth - has helped boost Westpac's New Zealand profit to $1.017 billion.
The Australian-owned bank said its cash earnings were up 5 per cent compared to the prior year to September 30.
Its net profit for the New Zealand division rose 3 per cent to $936 million.
The bank also boosted its net operating income by 4 per cent to $2.349b.
Westpac New Zealand chief executive David McLean said a three-year focus on business transformation was delivering benefits for the bank, its customers and communities.
"This project involved investing money into critical parts of the business to simplify the banking experience, streamline dated processes, and improve services and fees for our customers."
Westpac New Zealand's operating expenses fell 3 per cent to $936m, while its net interest margin increased by 12 basis points to 2.15 per cent.
The bank's deposits were up 6 per cent to $61.9b while its lending grew 4 per cent to $90.4 billion.
McLean said home loans and business lending both grew by 4 per cent over the past year.
"We are supporting our customers to save and invest, with deposit growth again outpacing lending growth over the last 12 months and customers using low interest rates to repay their mortgages faster."
McLean said generally favourable conditions on the farm had helped lift its agri lending by 5 per cent, while deposits from farmers increased 14 per cent.
"This reflects a good turnaround in the dairy sector from three years ago and a
broadly healthy agricultural sector," he said.
Funds in Westpac's KiwiSaver scheme also increased by 17 per cent to $6.1b, with membership increasing by 3584 people and the average balance now hitting $15,300.
McLean said it had been analysing customer data and proactively contacting individual customers through its "Value Me" programme to check if their bank account or KiwiSaver scheme best fit their needs.
"We've contacted more than 470,000 customers during the past year."
Westpac's profit follows ANZ last week reporting a near $2b profit and BNZ also cracking through $1b in annual earnings.
Westpac's result comes on the same day as a report on New Zealand bank culture and conduct is due to be released by the Financial Markets Authority and Reserve Bank of New Zealand.
McLean said it had been working closely with regulators.
"We are firmly focused on putting customers first and delivering positive customer outcomes.
"We will be working through any issues regulators identify to ensure we retain the trust of our customers and other stakeholders.
"Where any issues are identified we are committed to fixing those quickly."
Westpac's Australian parent made a net profit up 1 per cent of A$8.095b while its cash profit was flat on $8.065b.