Phumzile Mlambo-Ngcuka, who made history as South Africa's first female deputy president in 2005, said gender-balanced cabinets made better decisions not just for women, but for society as a whole.
Global progress on getting more women into top roles is frustratingly slow, she told the Thomson Reuters Foundation. But she believes Kamala Harris's appointment as the first female US vice president will make other countries take note and spur more women to consider running for office.
"It does help if a big country breaks the mould. It pushes other countries forward," she said.
Mlambo-Ngcuka said Harris, who is of Indian and Jamaican heritage, was a particularly important role model for young women of colour. "They now have someone who looks like them, who they can identify with," she said, adding that she had witnessed how her own appointment in 2005 had encouraged the ambitions of a younger generation.
"It was such a fulfilling feeling to hear young women (saying) 'Wow, this is on the table. I can also go for this'," Mlambo-Ngcuka said.
Only 22 countries have an elected woman head of state or government, while 119 nations have never had a woman leader, according to UN Women, which said gender parity would not be achieved for another 130 years at the current rate of progress.
The analysis also showed parity would not be reached in national parliaments before 2063, and in ministerial positions before 2077.
In early 2020, only 14 countries had cabinets where women held at least half of posts. They included Rwanda, Finland, Canada, Colombia and Peru. The United States is set to join the club after President Joe Biden pledged to pick a cabinet that "looks like America".
Mlambo-Ngcuka said women seeking office faced multiple hurdles, including a lack of support from political parties, which made it very important that countries introduce quotas for female representation.
She also urged governments to criminalise violence against women in politics and called on social media platforms to tackle rising cyber-abuse, much of it involving sexual innuendo and body-shaming, which deterred women from taking public roles.
Four in five women parliamentarians have experienced psychological violence linked to their job, one in four physical violence and one in five sexual violence, UN Women said, citing a 2016 study. "This is a way of intimidating women out of leadership even before they start," Mlambo-Ngcuka said.
"Governments and criminal justice systems have got to pay attention to (this), and make sure the perpetrators are actually brought to book."
Mlambo-Ngcuka said gender-balanced governments made better decisions because they were more representative of the people they served, and women brought fresh perspectives.
"You reduce the likelihood of missing out on the needs of some people because you just have never walked in their shoes," she added.
She said female leaders - from New Zealand's Jacinda Ardern to Germany's Angela Merkel - had rightly won praise for their handling of the Covid-19 crisis.
"Women tended not to focus on the politics, but just on finding solutions, so they would work with everybody," she added.
Getting more women into local government also makes a difference, Mlambo-Ngcuka said. In India, for example, women-led councils have pushed for better access to clean water - critical for preventing the spread of the virus.
Mlambo-Ngcuka said it was crucial that women play a leading role in building more inclusive post-Covid-19 economies, particularly as so many women had been pushed into poverty.
"If women do not recover from the poverty they've been thrown in because of Covid, many families and communities are going to be in a very difficult situation for a very long time. And that is going to be a problem for everybody," she said.