The King Richard star, who won best actor, took offence after the comedian joked about his wife Jada Pinkett Smith’s hair during the awards ceremony.
The comment struck a chord with Smith, 57, as Jada, 50, suffers with hair loss condition alopecia, which she publicly announced last year.
Smith stormed the stage and smacked the presenter in the face for his GI Jane joke towards his wife, but has now admitted he is embarrassed by his behaviour.
What did Will Smith say?
Smith addressed the incident in a post on Instagram on Monday, almost 24 hours after the incident, where he admitted his actions were inexcusable, while also saying sorry to Rock, 57.
The post said: “Violence in all of its forms is poisonous and destructive. My behaviour at last night’s Academy Awards was unacceptable and inexcusable.
“Jokes at my expense are a part of the job, but a joke about Jada’s medical condition was too much for me to bear and I reacted emotionally.
“I would like to publicly apologise to you, Chris. I was out of line and I was wrong. I am embarrassed and my actions were not indicative of the man I want to be. There is no place for violence in a world of love and kindness.
“I would also like to apologise to the Academy, the producers of the show, all the attendees and everyone watching around the world. I would like to apologise to the Williams Family and my King Richard Family. I deeply regret that my behaviour has stained what has been an otherwise gorgeous journey for all of us.
“I am a work in progress. Sincerely, Will.”
Formal investigation launched
The Academy has since announced it has launched a formal investigation into the incident and will be exploring “further actions and consequences”.
A statement released after the altercation read: “The Academy condemns the actions of Mr. Smith at last night’s show. We have officially started a formal review around the incident and will explore further action and consequences in accordance with our Bylaws, Standards of Conduct and California law."
Rock has declined to file a police report over the incident, the Los Angeles Police Department (LAPD) confirmed.
A full statement from the police force said: "LAPD investigative entities are aware of an incident between two individuals during the Academy Awards program.
"The incident involved one individual slapping another. The individual involved has declined to file a police report.
“If the involved party desires a police report at a later date, LAPD will be available to complete an investigative report."