The award, the inaugural UN Women's Empowerment Principles ''Benchmarking for Change'', was announced in New York.
In an interview with the Otago Daily Times, Mr Thorburn, the father of three daughters, said it was a proud moment and recognition of a plan he put in place at the BNZ in 2010.
New Zealand had led the way in women's issues in giving women the vote. It had had two women prime ministers, a chief justice and a female Speaker.
However, at a boardroom level, there was work to be done and business leaders needed to place an emphasis on promoting women.
''The process needs to be ongoing, as change doesn't happen overnight.''
When he surveyed BNZ staff in 2010, Mr Thorburn found that although half of all 5000 employees were women, only 10% of those were in senior management roles.
''We didn't have women leaders in major parts of the bank. Change was needed and I was happy to lead that change.''
Although Mr Thorburn recognised that gender equality was important, he also realised that with Auckland becoming one of the most diverse cities in the world, the bank should also work on race equality.
He established a diversity council in the bank made up of bank executives, not human resources staff. The council was a sub-committee of the business committee that reported directly to Mr Thorburn.
Senior leaders took part in an ''unconscious bias'' training.
There was a feeling within some areas of the bank that young women with children could not be fully focused on a banking career or that a young Pacific Islander did not have the presence to be a leader.
''We break down those barriers in the training. We look at the up-and-coming women in the bank, develop a career plan and provide a mentor. If they leave, we do an exit interview to find the reasons. We have a lot more succession plans in place for women,'' he said.
Half of the bank's executive team was now women but it was not always plain sailing.
The first response was that many people in the BNZ did not believe there was a problem. It was like ''the women who work for me don't want the job'', or ''they usually don't apply'', Mr Thorburn said.
''But we found in our survey that men who had been in the bank 10 years or more had networks. If they applied for a job, the person hiring them was usually a man. The one applying for the job could phone up his old boss asking him to put a good word in for him.''
Women did not have the same sort of networks, and if they did, they were less inclined to use them, he said.
''They applied for the job and if they got it they got it.''
Because there were thousands of things to do in a bank, Mr Thorburn made a conscious effort to push gender equality to the top of the list. The plan was reassessed annually and a report was made to the shareholder - the National Australia Bank - which approved the plan.
''We set a target three years ago to make significant change. We have made progress but it's a journey. There is still a long way to go,'' he said.
Women's Affairs Minister Jo Goodhew presented the award to Mr Thorburn yesterday. BNZ head of engagement Annie Brown was in New York to accept the award on behalf of Mr Thorburn and the BNZ.
