Coulson, 46, who edited the now defunct News of the World (NoW) tabloid before becoming Prime Minister David Cameron's official spokesperson, faces jail after the jury unanimously returned a guilty verdict against him at the Old Bailey court here. He was convicted of hacking phones between 2000 and 2006.
Brooks, 46, was found not guilty of four charges spanning an 11-year period at News International, including during her editorship of the NoW and The Sun.
Soon after the verdict, Cameron apologised over his decision to hire Coulson as director of communications at Downing Street, saying it was a "wrong decision".
"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 turn out not to be the case," he said.
"I always said that if they turned out to be wrong I would make a full and frank apology and I do that today. I am extremely sorry I employed him. It was the wrong decision and I am clear about that," Cameron said.
"I gave someone a second chance. It turned out to be a bad decision," he added.
Coulson, among seven defendants at the trial, was found guilty of a charge of conspiracy to intercept voicemails.
Brooks has been cleared by a jury of four counts including plotting to hack phones, conspiring to pervert the course of justice, and two counts of conspiring to commit misconduct in public office. Former NoW managing editor Stuart Kuttner was also found not guilty.
Employees of the newspaper were accused of engaging in phone hacking, police bribery, and exercising improper influence in the pursuit of publishing stories.
The 168-year-old NoW shut down in disgrace in July 2011 amid a public outcry.
There were dramatic scenes outside the court today as the flame-haired Brooks and her husband, Charlie - a racehorse trainer - who was also cleared, left the court.
Brooks appeared to mouth "thank you" to the jury and also held the hand of her former personal assistant Cheryl Carter, who looked close to tears.
Coulson stood emotionless as he absorbed the news.
The jury, which has been considering verdicts since June 11, is still contemplating further charges against Coulson and former NoW royal editor Clive Goodman of conspiring to commit misconduct in a public office by paying police officers for two royal directories.
The judge instructed them to deliberate further and gave them a majority direction, which means they can return with a verdict that is not unanimous.
During the course of the trial, the jury has heard details about high-profile victims of hacking during the trial, including schoolgirl murder victim Millie Dowler and various British royals, politicians and celebrities.
Coulson's conviction brings the number of former NoW journalists facing jail over phone-hacking to five.
Before the trial, three former newsdesk executives had pleaded guilty, as did the phone-hacker Glenn Mulcaire and a former reporter, Dan Evans, who confessed to hacking actress Sienna Miller's messages on James Bond star Daniel Craig's phone.
The scandal sent tremors across Britain's political elite. Prime Minister Cameron, known to be close to Murdoch and Brooks, was forced to order a public inquiry into press ethics in the immediate aftermath of the raging row.