Hundreds of people demonstrated in support of the Black Lives Matter movement following the death of George Floyd in police custody in the US.
The action at Cardiff Castle was organised following the death of unarmed Mr Floyd in Minneapolis, Minnesota, on 25 May.
There has been serious civil unrest across the USA sparked by the 46-year-old's death.
Ex-policeman Derek Chauvin, 44, is charged with murdering Mr Floyd.
Mr Chauvin, who is white, was shown in footage kneeling on Mr Floyd's neck. He and three other police officers have been sacked.
He is due to appear in court on Monday.
In Cardiff, the protesters sat peacefully in the city centre displaying 'Black Lives Matter' and 'Say their names' placards.
Speeches on standing up to injustice and racism were given.
One protestor, Donna Ali, said: "If you're silent, you're not going to change anything
"It's something we've experienced for many years, whether it's in the US or the UK.
"It's really heart-breaking that people can't see past the colour of skin."
And Garyn Young added: "It's important we show the unity and strength we have here.
"It's important for Welsh people to demonstrate - there's a BAME (Black, Asian, and minority ethnic) community here willing to show solidarity with the rest of the country.
"It makes me feel emotional, it's great to see so much passion and so much anger at what's happened."
South Wales Police reminded protestors of coronavirus legislation.
A spokesman said: "The event passed without incident with minimal disruption to the wider public."