At the same time, 2.3 million male workers will benefit, the Resolution Foundation report claims.
According to The BBC, the majority of employees would see their earnings rise in line with the minimum but some would gain from a “ripple effect” of wage rises.
The National Living Wage of £7.20 an hour comes into force in April 2016.
It will only apply to workers over the age of 25. The national minimum wage is currently £6.50 an hour, which will rise to £6.70 next month.
“Because of their concentration among the low paid, women will account for the majority of the winners,” said the think tank’s policy analyst, Conor D’Arcy.
“This will have a positive – though modest – effect on the gender pay gap, and will particularly help those working part-time.”
Analysis by the Resolution Foundation found that six million people – almost a quarter of all employees – will get a wage rise by the end of the decade, worth an average of £1,210.
A further 2.8 million employees already being paid the new minimum would gain as firms maintained pay gaps between different workers, the report said.
Workers in areas including Yorkshire and the Humber, Midlands and Wales were expected to be among those benefiting most from the higher wage, it suggested.
Earlier in the week, the government outlined plans for tougher penalties to be imposed on employers which fail to meet the National Living Wage requirements.
The plan for the wage, outlined in Chancellor George Osborne’s Budget, has received support, but the CBI said it was a “gamble” to place politics into the setting of a minimum wage level.
