She replaces George Stephanopoulos, who left the show in December to take over as co-host of ABC's "Good Morning America."
An Iran-born journalist whose expertise is in international stories, and who has complained about the lack of overseas news in the American news media, would seem an unusual choice for a job that has largely been devoted to discussions of political and domestic news. That also may represent a real opportunity.
"With Christiane, we have the opportunity to provide our audiences with something different on Sunday mornings," ABC News President David Westin said.
Amanpour, 52, said she was exhilarated by the challenge. "It's a once-in-a-lifetime and a unique opportunity," she said.
She had a high profile as CNN's top international correspondent in the days when there was only one cable news network, reporting from conflicts in Iraq, Afghanistan, Somalia, the Balkans and elsewhere.
Since moving to New York three years ago to be with her husband, former U.S. State Department spokesman James Rubin, Amanpour has been seen much less frequently. She hosts a daily program for the CNN International network. Highlights of those are shown for a half hour each Sunday afternoon on CNN's domestic network.
ABC has courted her for a job since back when Roone Arledge was head of the news division, more than a decade ago. She and Westin both said the time was right now.
"Of all the people I know in this business, Christiane knows herself and she knows the news," said Frank Sesno, former CNN Washington bureau chief. "I think it's a very interesting and wise move for her and I think it will be a very different kind of program. George was the consummate insider, a former White House staffer turned interviewer. Christiane is the exact opposite."
She's already a non-Washington insider, who will commute to her new job from a home in New York.
That could be a risk for ABC, whose Sunday morning program has generally run a strong second to NBC's "Meet the Press," with the competition closer since the death of NBC's Tim Russert. Amanpour downplayed the idea that "This Week" will dramatically change.
"This is something that people have come to really know and depend on," she said. "The creative DNA of the show will remain. What we want to do is broaden it even more."
Ian Cameron, executive producer of "This Week," said he looked back at tapes of the show when David Brinkley was host and found there was more news of the world discussed. The more intense domestic focus is a recent phenomenon, he said, perhaps partly in response to polls showing American news viewers with less of an interest in international news.
"That will be our challenge," Cameron said. "We'll need to explain to our viewers why we're doing these stories, why it's connected to their lives and what it means to them."
He minimized Amanpour's supposed lack of expertise in domestic subjects, noting she can become versed in them like she had to learn about different conflicts while traveling the world.
Amanpour was chosen over some internal ABC candidates, some of whom filled in since Stephanopoulos left, including Jake Tapper and Terry Moran. Former ABC "Nightline" host Ted Koppel was even in the mix at one point. Tapper will fill in as host until Amanpour takes over in August.
"It's a real good and challenging fit for her and a good and challenging fit for ABC," Sesno said. "I don't think the television audience needs another inside-the-Beltway, inside-the-filibuster conversation on Sunday."
Jim Walton, president of CNN Worldwide, saluted Amanpour and said her work burnished the CNN news brand and gave it authority.
"CNN and Christiane helped make each other great," he said.
