Rebekah Brooks, Coulson’s predecessor as editor at the News of the World, was found not guilty of all four charges she faced.
Coulson faces a maximum of two years in prison for the crime. He is still awaiting a verdict for the charge of misconduct in public office following an eight-month trial.
Cameron quickly issued a full apology for employing Coulson as his head of communications between 2007 and 2011, telling journalists: “I take full responsibility for employing Andy Coulson. I did so on the basis of undertakings I was given by him about phone hacking and those turned out not to be the case.
“I always said that if they turned out to be wrong that I would make a full and frank apology and I do that today. I am extremely sorry that I employed him. It was the wrong decision and I’m very clear about that.”
The Prime Minister, who will face questions from Labour leader Ed Miliband in parliament today, employed Coulson six months after he resigned from the now defunct News of the World, following the conviction of Clive Goodman, the paper’s royal correspondent, for phone hacking offences.
Coulson had maintained throughout the trial that he did not know about phone hacking, before eventually admitting he knew about a reporter hacking the phone of the home secretary at the time of the Iraq war.
Cameron will take on Miliband, who has said that the verdict taints the current government, at Prime Minister’s questions today. He will then face leaders in Europe in a showdown over the appointment of Jean-Claude Juncker to EU president, a decision he has promised to block.
Meanwhile News Corp boss Rupert Murdoch could face an interview with police about his newspapers’ actions, according to The Guardian.
Scotland Yard and News Corp declined to comment.