"Dame Margaret was tireless campaigner for women's rights. She founded the Women's Electoral Lobby in 1975, and was Minister of Women's Affairs from 1987-1990," Labour leader David Shearer said.
"She went on fighting to advance the position of women internationally, serving with the United Nations Development Fund for Women and the UN International Research and Training Institute for the Advancement of Women.
"Dame Margaret made a difference. She stood up for what she believed in, and fought to build a fairer and more just world.
"The Labour Party joins Dame Margaret's family in mourning her passing.
"She was a woman of conviction who lived a life of leadership and service."
Her funeral will be held at Old St Paul's in Wellington at 2pm on Friday.