Andy Coulson, the former editor of the News of the World newspaper, who went on to work for Prime Minister David Cameron, will go to prison for 18 months for plotting to hack phones.
An important trial has been going on for many months, after the voicemails of top celebrities, royalty and even crime victims were hacked into.
The News of the World was shut down in 2011 after the scandal was revealed.
Three other journalists from the paper were also sentenced on Friday.
The trial was trying to find out if the people in charge of The News of The World knew that journalists were hacking into mobile phones to get juicy stories.
Two journalists, Neville Thurlbeck and Greg Miskiw, will go to prison for six months each; while another, James Weatherup, was given a four-month suspended sentence, meaning he won't got to jail unless he reoffends.
Private detective Glenn Mulcaire, hired by the paper to try and get hold of people's phone numbers, was also given a six-month suspended sentence: he has to do 200 hours unpaid community service, and if he's caught doing the same crime again, he'll go to prison.
'Full and frank apology'
After the trial found Mr Coulson guilty, the PM said: "I am extremely sorry I employed him. It was the wrong decision and I am clear about that."
Before getting the job as Mr Cameron's head of communications, Mr Coulson told the PM he'd not been involved in hacking phones.
"Knowing what I know now, and knowing that those assurances weren't right, it was obviously wrong to employ him," Mr Cameron said.
One of the other major people on trial, Rebekah Brooks - who was in charge of News International, the company that made the News of the World - has been cleared of all the charges against her.