Scott Law was found guilty of common assault after he and pundit Keane clashed on September 3 last year.
The fracas began when Keane and fellow Sky Sports pundit Micah Richards were walking to do the final match analysis after Arsenal’s 3-1 victory over Manchester United, the trial at Highbury Corner Magistrates’ Court heard.
The former Republic of Ireland and Manchester United midfielder, who was working as a pundit for Sky Sports, was headbutted through doors at the Emirates Stadium by Law, of Waltham Abbey, Essex.
Law’s defence team said CCTV footage from inside the stadium, shown in court, displayed Keane elbowing the defendant in the face.
Delivering his verdict, District Judge Angus Hamilton said he believed Law had been “untruthful about what happened” during the match.
Scott Law, pictured, was found guilty of headbutting Roy Keane (Lucy North/PA)
He continued: “There was no reason Mr Keane should have picked on him in particular.
Keane “was calm and not agitated” when he left the studio, he added.
The judge said Keane’s reputation as the so-called “hard man of football”, was “years ago and was confined to the football pitch”.
“I’m sure Mr Law assaulted Mr Keane.”
Law did not react as the verdict was delivered.
Keane said he was left “in shock” by the assault.
Giving evidence, the 52-year-old told the court: “There was lots of noise and shouting, as you would expect at a football match.
Football pundit and former Manchester United midfielder Roy Keane, leaves Highbury Corner Magistrates’ Court (James Manning/PA)
“I was just walking and, before I knew it, I was hit. I felt the contact and fell back through some doors.
“I was absolutely not expecting it. The only way I can describe it is that I was in shock. I didn’t expect it to happen, not when I was in my workplace.”
He said he suffered bruising on his chest and arms as a result of the incident.
Giving evidence to the court, former Manchester City defender Richards denied accusations by Law’s defence barrister that he had claimed to see the headbutt because he was “Roy’s mate” and had become his “puppy” and “stooge”.
The ex-England defender said he “grappled” with Law following the alleged incident.
Richards said he was in “disbelief” at what he witnessed, and “felt sorry for Roy” who he described as a friend.
The pundit said “you wouldn’t get sent off” for actions in CCTV footage, shown in court, that Law’s defence team alleged showed Keane elbowing the defendant in the face.
Following the match, footage was widely shared on social media of Richards stepping in to calm an apparent confrontation.
Law, who was sat beneath the Sky Sports studio during the match, said Keane was “very animated” and “angry” throughout the game, adding he had “never really seen that behaviour from someone who was working in the Sky box”.
He told the court: “Mr Keane was puffing his cheeks out. He was right up against the glass. He was banging on the window.
“Mr Keane picked me out and started telling me to see him outside. He was pointing to doors in the box.”
Law said he went inside the stadium to go to the toilet and encountered Keane who “collided into him”.
Prosecutor Simon Jones KC asked Law: “Are you seriously saying that Roy Keane ran into the top of your head?”
Law, who cried while being questioned, said: “I put my head down in a defensive manner to protect my face.”
Jones said Law’s “ridiculous” defence had “changed dramatically” from a prepared statement he gave to police the day after the incident.
Asked about the apparent differences in this statement, Law replied: “I’d had no sleep – I was guilty by media.
“It was the worst night of my life.”
Law, a civil engineer, said he had been an Arsenal fan “from birth” and said his Emirates Stadium season ticket was his “prized possession”.
He told the court: “It’s the main part of my social circle. My wife organises her diary around Arsenal fixtures because she knows I’ll be there.”
As well as being barred from attending football matches, Law was ordered to complete 80 hours of unpaid work, and must pay legal costs of £650 plus a victim surcharge of £114.
Kevin Christie, Crown Prosecution Service London North football lead prosecutor, said: “This gratuitous and senseless act of violence was completely unacceptable.
“When anyone attends a football match, either to work or to support a team, they should be able to feel safe and secure in that environment.
“The Crown Prosecution Service works in close partnership with the police to ensure that all perpetrators of violence at football grounds are brought to justice.”