About 30,000 Westpac NZ customers will receive replacement cards following a data security incident related to Ticketmaster in June.
Those who purchased, or attempted to purchase, tickets between September 2017 and June 23, 2018, were potentially at risk of fraud.
Tiffany Ryan, Westpac NZ head of financial crime and security, said while the risk of fraud was low, Westpac wanted to take an extra proactive step to protect customers.
"Westpac NZ is in the process of proactively replacing around 30,000 cards, where we have concerns that a customer's card details may have been compromised," Ryan said.
"We have strong fraud controls in place, but we wanted to take an extra proactive step to protect our customers and provide them with peace of mind around this issue."