The jury delivered their verdicts after eight days of deliberations and nearly six months of evidence sparked by the scandal that led to News Corp boss Murdoch shutting down the Sunday tabloid in disgrace in July 2011.
Coulson, 46, who was forced to resign as British Prime Minister David Cameron's media chief over the scandal, now faces jail following his conviction at the Old Bailey court in London.
But the flame-haired Brooks, once one of Australian-born Murdoch's closest aides, will walk free after being cleared of conspiring to intercept mobile phone voicemails and of plotting to pay officials for information.
The trial had its own dose of scandal worthy of the now-defunct News of the World when the jury heard that Brooks and Coulson had an extra-marital affair while working at the paper.
The case centred on News of the World's efforts to hack the phones of Britain's royal family, politicians, celebrities and victims of crime, including a murdered schoolgirl, and families of people killed in the July 7, 2005 London bombings.
It also raised questions about the judgement of Cameron in hiring Coulson, who resigned as editor of the News of the World in 2007 after two people were convicted of phone-hacking.
Brooks's current husband Charlie, a racehorse trainer, and News International director of security Mark Hanna were also cleared of perverting the course of justice by allegedly trying to hide evidence from the police.
Her former personal assistant Cheryl Carter was cleared of conspiracy to pervert the course of justice.
The paper's retired managing editor Stuart Kuttner was also cleared of conspiracy to hack phones.
There was no immediate reaction from Cameron or from Murdoch after the verdicts, which represent a setback for British police and prosecutors after a high-profile, three-year investigation.
During the investigation, Brooks had to quit as head of News International, the former British newspaper wing of Murdoch's media empire.
The jury at the Old Bailey court in London heard highly detailed evidence about the workings of the paper, known for its celebrity scandals and kiss-and-tell stories.
Murdoch shut down the News of the World in a firestorm of disgrace and a boycott by advertisers just over three years ago after it emerged that the paper had hacked the voicemails of murdered schoolgirl Milly Dowler.
The hacking scandal also prompted a judge-led inquiry into the ethics of Britain's famously aggressive press, which made recommendations for reforming the way it is governed. They are yet to be put into force.
But Judge John Saunders had urged the jurors when he sent them out on June 11 to "put out of your head anything you have heard outside court".
The jury on Tuesday was still considering further charges against Coulson, a married father-of-three, and the paper's then royal editor, 56-year-old Clive Goodman, for committing misconduct in a public office by paying officers for two directories of phone numbers linked to the royal family.
Prime Minister David Cameron apologises
Prime Minister David Cameron said on Tuesday he was wrong to hire Andy Coulson as his media chief in 2007 after Coulson was found guilty of being part of a phone-hacking conspiracy.
Political opponents have long questioned Cameron's judgement in taking on Coulson after he resigned the editorship of Murdoch's now defunct News of the World newspaper when two of its employees were jailed for phone-hacking.
In a pre-recorded clip to British TV, Cameron said he made a "full and frank" apology for hiring Coulson.
"I'm extremely sorry that I employed him, it was the wrong decision," said the British leader.
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