In the workplace, women are 26 percent less likely to be employed than men and fewer than one-third of managers are women, even though they are likely to be better educated, said Guterres, citing a recent International Labour Organisation study.
"Even governments that are vocal supporters of this agenda fail to back their words with action where it counts," said the UN chief, who has declared himself to be a proud feminist.
He singled out nationalist, populist and austerity agendas that are "aggravating inequality, splintering communities, curtailing women's rights, cutting vital services."
President Donald Trump's administration has sought in UN rights committees to strip references to sexual and reproductive health, arguing that it has been used to promote abortion.
In the run-up to CSW, more than 30 female leaders signed an open letter calling for a fightback against the erosion of women's rights, led by former foreign minister Susana Malcorra, New Zealand's ex-prime minister Helen Clark and Bulgarian politician Irina Bokova.
"We see now, more than a quarter of a century after Beijing, more movements gaining traction which seek to halt the gains made and erode the rights won by women," said the letter.
"We seek to underscore that the risk posed by policies that seek to halt and erode gender equality is a risk not only to women, but also to all of humanity."
This year's focus is on social protection and access to public services for women and girls, but the rise of the #MeToo movement and record numbers of women elected to the US Congress are garnering attention.
The gathering will pave the way to the 25th anniversary next year of the landmark Beijing declaration that outlined a roadmap to equality.