While she was working there, the investigation found that other staff had accessed the personal records at the agency's contact centre and the information was passed to other parties.
An ex-staff member told the Herald that client files were also used "like a dating site" by officers looking at information on wealthy applicants and recommending them to single colleagues.
Only selected immigration staff have access to client files and can access them only when it is work related.
However, an average of between five and six staff each year are found by the agency to have breached privacy guidelines.
The number spiked to nine staff last year, four of whom were issued final written warnings. Another one resigned.
Other previous disciplinary action taken by the agency included warnings, dismissal and counselling.
A code-of-conduct reminder was emailed to all staff in 2006, when there were six breaches.
"It's a very small group of people who, on occasion, breach our guidelines," said head of Immigration NZ Steve Stuart.
"But where we find evidence of inappropriate use of any of our official information, we move on this quickly, both to protect the integrity of the information we hold in trust and the reputation of our people and organisation."
Mr Stuart said staff who did not have access to client records were given "very clear instructions and guidelines" for appropriate use of the system.
The Herald revealed last week that a former staff member who resigned after being caught looking at client files joined the Ministry of Justice where she was investigated for the same breaches.
PRIVACY BREACHES
* 2003/4 - 5 cases
* 2004/5 - 5 cases
* 2005/6 - 6 cases
* 2006/7 - 5 cases
* 2007/8 - 2 cases
* 2008/9 - 7 cases
* 2009/10 - 8 cases
* 2010/11 - 4 cases
* 2011/12 - 7 cases (9 staff)
Source: Immigration NZ