The Vossi Bop singer, 29, spoke at the march saying: “Chris has a mother, he has a family, he has brothers, he has friends, people who knew him in real life, who for them it’s unbearable.”
He said there was no way to “sugarcoat” what had happened to Mr Kaba and urged them to “have stamina” in their efforts to raise awareness of his death and the events surrounding it.
“Everyone here today, I would encourage everyone to have stamina, and I know it’s a very difficult thing to say… But when these people do these things, they get away with it, because what happens is we do this once, we get tired, we tweet, we get tired, we do it for a week, we do it for two weeks, we do it for a month, and they know we get tired,” he said.
“What they’ve done is they’ve killed someone. We can’t sugarcoat it,” he added.
Hackney Labour MP Diane Abbott and Streatham Labour MP Bell Ribeiro-Addy were also at the event in the capital, which saw supporters in the crowd carrying signs saying “Justice for Chris Kaba” and “Black Lives Matter”.
Crowds gathered outside Scotland Yard to demand justice for Mr Kaba, who was 24 and due to become a father within months.
The Independent Office for Police Conduct (IOPC) has launched a homicide investigation into the incident.
The police watchdog also previously confirmed that no gun was found in the Audi that Mr Kaba was driving when he was fatally shot in Streatham Hill on Monday night.
Met Assistant Commissioner Amanda Pearson said on Friday the officer involved is not currently on operational duties and their work status will be carefully considered going forward.
She said the force was cooperating fully with the IOPC investigation.