Chris Rock finally hit back at Will Smith on Saturday in a brutal stand-up routine, a year after the actor slapped him in front of a global TV audience for the Oscars.

The comedian came out swinging, accusing the Hollywood star of "selective outrage" when he reacted to a jibe about Jada Pinkett Smith's shaved head, and saying Smith lashed out at a shorter man because he was annoyed his wife had cheated on him.

"Will Smith practices selective outrage," Rock told an audience in a show that was streamed live on Netflix.

"Everybody that really knows, knows I had nothing to do with that. I didn't have any entanglements," he said, referring to Pinkett Smith's acknowledged marital infidelity.

Rock was presenting an Oscar in Hollywood last March when he made a crack about Pinkett Smith's closely cropped head.

The "Men in Black" star mounted the stage and slapped the comedian hard across the face, before returning to his seat and yelling obscenities at the presenter.

A few minutes later, Smith was presented with an Oscar for best actor for his role in "King Richard."

He later apologized to Rock, but was banned from the Oscars for a decade.

Rock was praised for his measured response on the night, and has maintained near silence on the issue in the year since.

But on Saturday night's livestream from Baltimore, he let rip.

"People ask 'Did it hurt?'. It still hurts," he said.

"Will Smith is significantly bigger than me. Will Smith played Muhammad Ali in a movie. You think I auditioned for that?"

The comedian said Smith had been widely mocked after an episode of his wife's podcast in which the couple talked about her affair and how it affected him.

"Why would you do that?" he asked. Many people have been cheated on, but the Hollywood power couple are the only ones who discussed it in public that way, he said.

"Everybody in the world called him a bitch. They called his wife a predator. Everybody called him a bitch," he said, noting that he had tried to offer condolences after news of the affair became public.

Rock said the animosity from Pinkett Smith stemmed from a few years earlier when she had called on him to boycott the Oscars because her husband had been overlooked for his 2015 movie "Concussion."

"She said... a grown ass man should quit his job because her husband didn't get nominated for 'Concussion.' Then (Smith) gives me a concussion," he quipped.

"What the fuck? So did I do some jokes about it? Who gives a fuck? That's how it is; she starts it, I finish it. Nobody was picking on her."

Rock, who at times appeared genuinely angry, said before last year, he had always loved Smith, first as a rapper, and then as an actor.

"He'd made some great movies. I've rooted for Will Smith my whole life," but now, he said, he was rooting for the slave master who beats Smith's character in his latest movie, "Emancipation."

This year's Oscars will be held on March 12.