MPs suspended their questioning of News Corporation chairman Rupert Murdoch for 15 minutes after a protester lunged towards him with a shaving foam pie.
The man rushed forward from the public gallery two hours into the session and was fought off by a group of people including Mr Murdoch's wife Wendi Deng.
Jonathan May-Bowles, 26, who describes himself as an activist and comedian was charged with a public order offence.
The Speaker has asked for an investigation into the incident.
He wrote on Twitter under the account Jonnie Marbles just before the incident: "It is a far better thing that I do now than I have ever done before #splat."
His membership of the Labour Party was suspended on Tuesday night.
A spokesman said: "He was a member although his subscriptions were in arrears. It was despicable behaviour and he has been immediately suspended."
The session had been going for two hours when the protester reportedly shouted "you naughty billionaire" as he approached Mr Murdoch - who was being questioned in a room in Portcullis House, a building adjacent to the Houses of Parliament where many MPs have their offices.
Mr Murdoch's wife, dressed in a pink jacket and seated behind him during the session, leapt up to defend her husband and appeared to slap the assailant on his head. She also grabbed the plate used in the attack and hit the assailant with it.
The shaving foam hit Mr Murdoch's suit jacket and he later resumed the session in his shirt and tie.
The man was fought off by a group of people including Mr Murdoch's wife Wendi Deng.
At the end of the questioning, committee member Labour MP Tom Watson joked to Mr Murdoch: "Your wife has a very good left hook."
Seconds after the incident occurred, Tory MP John Whittingdale - who chairs the Commons media committee and was overseeing proceedings - suspended the session.
People were quickly ushered out of the room, the BBC's political editor Nick Robinson said, and reporters and members of the public were not re-admitted.
Scotland Yard have confirmed that a 26-year-old man was arrested on suspicion of assault.
Nick Robinson said Rupert Murdoch had remained calm but that his son James - who was sitting next to his father at the time - seemed incensed by the incident.
James Murdoch said he was angry that Commons security staff had failed to protect his father.
Labour MP Chris Bryant, who was present in the committee room, said the attacker tried to shove a plastic plate with shaving foam on it in Rupert Murdoch's face.
He said: "It's a contempt of Parliament to do something like this."
Asked about security levels in the building, he said: "I guess they weren't looking for shaving foam."
Mr Whittingdale apologised to the tycoon, saying the incident had been "wholly unacceptable".
Tory MP Louise Mensch said it showed "real guts" for the Murdochs to continue answering questions, saying he had been the victim of a "common assault".
The public was later excluded from a subsequent hearing in which former News International boss Rebekah Brooks answered questions.
After the session, Mr Whittingdale said: "I was very angry that that occurred, it does no credit to the committee or Parliament that it took place.
"I shall certainly be making a report to the Speaker and I hope there will be an investigation as to how the people responsible were able to get into the room and carry it out."
Mr Whittingdale has been called to see Speaker John Bercow following the incident.
A spokesman for the Speaker said: "The Speaker is very concerned at what has occurred and has asked for the incident to be thoroughly investigated. It is wholly unacceptable that a member of the public should treat a witness in this way."