Employers will have to provide information about workers' pay to show whether their male and female staff are receiving equal rates, if Labour has its way.
The policy – released today to mark Women's Suffrage Day – would expose inequalities in the workplace, said the party's women's affairs spokesperson, Carol Beaumont.
"New Zealand women still, on average, earn less than men and are often less likely to hold leadership roles," she said.
Beaumont said there was a 12 percent pay gap between the average hourly earnings of men and women. Women also tended to be concentrated in low-paid jobs and there were far fewer in leadership positions.
"We will reinstate the goal of having 50 percent of the positions on state sector boards taken up by women and reverse National's cuts to the Training Incentive Allowance which make it harder for women to access education."
Companies could also be required to report on the number of women they employed and at what levels.
Council of Trade Unions president Helen Kelly said international experience showed legislation was necessary to close the gender pay gap.
"It is time to guarantee that women are valued and paid fairly and equally. But these changes won't just magically happen."
Minister of women’s affairs Hekia Parata told the APEC Women and the Economy Summit in San Francisco this week that New Zealand women were doing well.
"The gender pay gap is the lowest it has ever been. But there is always more that can be done and while government can play its part businesses must take the lead."
The summit drew more than 600 participants and was chaired by US Secretary of State Senator Hillary Clinton.
It concluded with the adopting of the San Francisco Declaration, a commitment by all 21 APEC nations to take action to maximise women's contributions towards economic growth. The four areas involved are: initiatives to improve access to capital, access to markets, capacity and skills building and women's leadership.
“One of the most impressive statistics of the summit was that the potential of harnessing women’s potential is bigger than the combined effect of the economies of Brazil, Russia, India and China," Parata said.
“A recent report from Investment Bank Goldman Sachs says we could increase our GDP by 10 percent by increasing women’s participation in the economy."
Last month NZX chief executive Mark Weldon told The Listener the stock exchange planned to propose new rules that will require all publicly-listed companies to share how many women and minorities they have in senior roles and as directors.