Pomeroy said he was looking for a "win-win" situation where both the bank's customers and kiwi developers could gain from the process.
The Westpac App Challenge is open to individuals, teams and organisations and entries close September 13.
About five entries will be chosen to give a 15-minute presentation to judges and at least two apps will then be chosen for development.
Winners will receive $10,000 and the opportunity to work with Westpac while it is implemented.
Pomeroy said the winners would retain ownership of the intellectual property rights in the app which could then be used outside New Zealand and Australia.
The competition brief had been kept wide to encourage innovative and creative thinking, he said.
"A fully operating app is not essential although the more developed the concept the better."
Westpac said it would be travelling the country talking to incubators, developer and designer groups, tertiary institutes and schools to encourage entries.
Judges include Pomeroy, Geekzone founder Mauricio Freitasm, and Optimal Experience's Michael Dutton.