CNN nailed down the final piece of its prime-time makeover on Wednesday, after months where it was clear the "America's Got Talent" panelist was its top choice. King, who announced in June he was leaving "Larry King Live," will have his final show on Dec. 16.
Negotiations dragged while CNN worked out a deal that allows Morgan to continue on "America's Got Talent" and his British talk show, "Piers Morgan's Life Stories," on Britain's ITV.
"I didn't come here to lose," he said. "I have always spent my life in ferocious ratings or circulation wars. It's what gets me going in the morning, and I want to combine brilliant interviews with great ratings."
That would be fine with CNN; King was once cable TV news' top gun but now runs third in his 9 p.m. ET time slot. Fox News Channel's Sean Hannity has averaged 2.27 million viewers this year at that hour, MSNBC's Rachel Maddow has 931,000 viewers and King averages 702,000, according to the Nielsen Co.
Another prime-time CNN show with former New York Gov. Eliot Spitzer and columnist Kathleen Parker is starting on Oct. 4. CNN has struggled in prime-time with news viewers more interested in opinionated shows on Fox and MSNBC.
Morgan said following King is "like replacing Frank Sinatra at the Sands." He said he considered it the biggest interviewer job in the world, and one that he's long had his eye on.
CNN U.S. President Jon Klein said Morgan had a "persistent agent." The agent, John Ferriter, e-mailed Klein with links to some of Morgan's interviews earlier this year, before it was known CNN was considering replacements for King. Klein said he "was just blown away by his talent, his ability to hone in on facets of people's personalities you never knew were there."
Morgan will be based in New York and also do work in Los Angeles and London. He'll do a mixture of celebrity and news interviews and said he looks forward to contributing on nights when news is breaking. Some of his shows will be live and some, particularly when "America's Got Talent" is on the air in the summer, will be taped.
He said he has a "very personal style" of interviewing familiar to British audiences that he hopes will be a pleasant surprise to Americans.
"It's a mixture of probing journalistic rigor with a twinkle in the eye and a little bit of mischief, not afraid to have fun where it's appropriate," he said. "(I'm) looking for revelations and candor and want to set the news agenda. That's my idea of why you should interview people. Don't make it boring. The enemy is apathy."
Morgan's ascent to American fame has astonished many in Britain, where he is remembered - not always fondly - as a high-flying tabloid newspaper editor whose career was tainted by scandal. Morgan worked on local newspapers in the 1980s, then became showbiz editor of The Sun, Britain's biggest-selling daily tabloid. He was named editor of its Sunday stablemate, the News of the World, in 1994 at age 28, and took over the Daily Mirror the next year.
His tenure there was long, but rocky. His coverage of the royal family, in particular, was sometimes criticized as intrusive. In one famous coup, one of the paper's reporters got a job as a footman at Buckingham Palace and smuggled out pictures of Queen Elizabeth II's breakfast table, royal bedrooms and a rubber duck in the royal bath. Some protested at the invasion of royal privacy, but Morgan said the newspaper had performed a public service by revealing lapses in security.
In 2000, a Mirror business column touted a company in which Morgan had just bought shares. The two journalists behind the column were fired, but Morgan stayed, although he was criticized by a professional watchdog.
Later, the paper was sued by Naomi Campbell for breach of privacy after it printed photographs showing her leaving a drug counseling meeting. She won, but an unrepentant Morgan greeted the verdict with the observation: "This is a very good day for lying, drug-abusing prima donnas who want to have their cake with the media, and the right to then shamelessly guzzle it with their Cristal Champagne."
In 2004, he was forced to quit after the Mirror ran pictures of British soldiers allegedly abusing Iraqis. They turned out to have been faked.
Since then, he has written a best-selling memoir about his career in tabloids, "The Insider," and built a successful TV career in Britain as well as the U.S. Besides his interview show in Britain, he's also a judge on "Britain's Got Talent."
He continues to write weekly columns on sports and on his own life for the Mail newspaper and will also write regular columns for CNN.com, CNN said.
Associated Press writer Jill Lawless in London contributed to this report.