The announcement from Deirdre Toner came after personal data on all serving members of the PSNI was mistakenly published earlier this month in response to a freedom of information request.
Details of the 9,483 people included the surname and first initial of every employee, their rank or grade, where they are based and the unit they work in.
The Police Service of Northern Ireland has confirmed the list is in the hands of dissident republicans, who continue to target officers.
Police officers and their representative organisations have spoken out in recent weeks over concern for their safety.
Earlier this week a man appeared in court in Co Antrim charged with two terror offences relating to the data breach.
A number of other data breaches have since come to light, including the loss of a police officer's laptop and notebook which contained details of 42 officers and members of staff after the items fell from a moving vehicle last week.
Chief Constable Simon Byrne appeared before the Policing Board on Tuesday, his second meeting since the major breach came to light.
He left the premises of the oversight body in Belfast without taking questions from media.
Ms Toner said Mr Byrne "retains the confidence of the board", but described exchanges as "crunchy".
"It's been a long day," she told reporters after the meeting, adding that a "wide range of issues" were discussed.
"It was constructive, proactive. Yes, it was certainly crunchy. There's no doubt about that.
"This breach and the subsequent breaches have damaged the reputation of the service and impacted the confidence of officers, staff and others in the service's ability to protect personal information."
Ms Toner said the independent review of the circumstances of the data breaches will be led by City of London Police Assistant Commissioner Peter O'Doherty.
It will look at process and actions leading to the breach and if any organisational, governance or management issues allowed it to happen.
Ms Toner said it will identify any action required to prevent further breaches and build more robust risk mitigation systems.
She said: "The review team have been tasked to have an initial report back to the board within one month. A final report is expected by the end of November and will be made available for public release."
She said these measures are essential to "help rebuild trust and confidence" in the PSNI.
The board will put in place monitoring measures to ensure "effective implementation of the recommendations" of the review.
Ms Toner added: "While much remains to be done, the board acknowledges the comprehensive response that has been mobilised and delivered by the PSNI."
She said the data breaches will be a standing agenda item on the monthly public and private accountability sessions with the Chief Constable for "as long as is necessary".
Northern Ireland's Chief Constable Simon Byrne has said he "recognises the gravity of the situation and challenges ahead" following a major data breach.
In a statement after attending a meeting of oversight body the Northern Ireland Policing Board, Mr Byrne said he gave an update on the service's immediate response, the criminal investigation and "approach to begin recovery".
"It was a constructive meeting," he said.
"I recognise the gravity of the situation and the challenges ahead.
"The independent review led by Assistant Commissioner O'Doherty, City of London Police, will provide answers to the questions.
"The service executive team and I are grateful for the support of the board.
"I would also reiterate my thanks to officers and staff who continue to serve the public around the clock."