More than 1500 people linked arms in a chain snaking around the edge of the park, while chanting "we are unbroken", to mark the second year of the Sydney Women's March.

The rally stood as an act of solidarity with protests across the world on Sunday, as thousands turned out across the US to demand equal rights and express anger and defiance at President Donald Trump.

Many of the protesters wore pink knit "pussy hats," which were created for last year's march as a reference to a comment made by Trump about female genitalia.

Women and men of all ages took to the Sydney rally waving colourful signs, with slogans such as "Fight like a girl", "Time is up", "If you're not angry, you're not paying attention", "Forwards not backwards" and "Don't mansplain my rights to me".

Alex McKoy, 11, joined the rally while on holiday in Sydney, having previously participated in "many" women's marches across the US with her mother, Caitlin.

"I want activists to feel good about what women have accomplished in the past years - in 2016, 2017 and now 2018, and further in the future," Alex said.

As a "woman of the future", Alex believes young people have every reason to join the women's marches, even bringing her Sydney friend Indie Morgin, 16, to her first rally.

"Coming to these rallies shows them how powerful anybody in any culture, religion, race or gender ... at a young age or old, can be," she said.

"No one is more powerful than anyone else, everyone is equal."

"This is what a feminist looks like," Alex and Indie chanted with the crowd.

Co-founder of the Sydney Women's March, Mindy Freiband sees recent international movements such as "MeToo" and "Time's Up", which have occurred since their inaugural marches last year, as "inspiring", but notes there is still a long way to go.

"It's ironic that it took so much bigotry and sexism to get women reignited, but I think this wave of women's action is so strong and powerful," Ms Freiband said.

"But this is a cultural shift, and it's going to require everyone to participate, in small ways and big."

University student Jasmine Noud told the crowd to remain "unbroken ... as individuals, and as a community", despite ongoing bigotry still visible across the world.

"Donald Trump is just one symptom of a sick system. A system where sexual abuse ... is normalised, where women's right to autonomy over their own bodies is dismissed and denied by lawmakers, where our very humanity is considered up for debate," she said.

"But we're still all here, and we're standing just as strong a year on."

Sydney locals Nick and Stephanie Michaloudakis brought their three daughters - aged four, two and six months - for what they hoped was their "first and last" march.

"We don't want our daughters to be here doing this when they're our age, basically. We want this to be their last march," Mrs Michaloudakis said.

"It's a harder world for women if you have to be on guard all the time, and I want my girls not to be worried about things like [harassment]," she said.

"It's about building comfortable confidence for their future, and not being intimidated by anyone," said Mr Michaloudakis, holding a sign, saying "Raising strong women".

"That's the end game - they're comfortable, confident, and not afraid."