CNN chat show host Piers Morgan told the British press ethics inquiry that he had no reason to believe phone hacking went on at the Daily Mirror during his editorship.
In a robust performance, Morgan refused to elaborate on the circumstances in which he heard a voice message left by Beatles star Paul McCartney for his then-wife Heather Mills.
Morgan, who edited the Mirror tabloid between 1995 and 2004, said he felt "like a rock star having an album brought out from his back catalogue of all his worst-ever hits", in sometimes terse exchanges.
Giving evidence to the inquiry in London via video-link from the United States, Morgan, who also was editor of the now-defunct News of the World from 1994 to 1995, said he was unaware of any phone hacking at the Mirror.
"To the best of my recollection, I do not believe so," he said. Asked if he had ever seen phone hacking going on, he said "no", adding that he was "100 percent" sure.
"Not a single person has made a formal or legal complaint against the Daily Mirror for phone hacking. Not one."
The inquiry into the ethics, culture and practices of the British press, being heard by judge Brian Leveson, was set up by Prime Minister David Cameron following the closure of the News of the World in July.
Morgan said he did not believe he had listened to illegally-obtained voicemail messages, and said it didn't follow that listening to one person speaking to somebody else was unethical.
He was asked about a message he heard which was left by McCartney for Mills when the couple were suffering problems with their marriage.
Morgan refused to go into details, saying he would not compromise his source.
Leveson asserted that only Mills or someone authorized by her would lawfully be able to listen to it and added that he was happy to call Mills to give evidence.
"What do you expect me to say?" Morgan said. "In their divorce case, Paul McCartney stated as a fact that she had recorded their conversations and given them to the media."
Morgan said he was never "directly involved" in hiring private investigators at the red-top tabloid but admitted using the services of a man named Benji "The Binman", who would go through celebrities' trash.
"Did I think he was doing anything illegal? No. Did I think it was on the cusp of unethical? Yes," Morgan said, adding: "If you threw something away you are disregarding it and you clearly have no use for it and it is going off to the rubbish tip."
Morgan said he had "very little sympathy" with celebrities who sell their wedding photos to the media "and then expect to have privacy if they get caught having affairs".
Celebrities "are the very last people who should be protected by privacy law", he said.
Meanwhile the owner of the News of World said it had settled phone hacking claims brought by seven public figures.
News International, the British newspaper unit of Rupert Murdoch's News Corp, agreed payouts with James Hewitt, the former lover of Diana, princess of Wales, and late football icon George Best's son Calum.
Paul Dadge, who helped survivors of the July 2005 bombings in London, television personality Ulrika Jonsson, model Abi Titmuss, former lawmaker Mark Oaten and theatrical agent Michelle Milburn were the others whose claims were settled.
Separately, a court heard ex-England footballer Paul Gascoigne was close to a reaching a deal.
News International has already settled dozens of compensation claims and has set up a compensation scheme for victims of phone hacking in a bid to avoid further costly civil lawsuits.
Police said earlier this month they believe about 800 people had their voicemail hacked into by the News of the World.