CHICAGO (AP) — Oprah Winfrey announced yesterday that her powerhouse daytime television show, the foundation of a multibillion-dollar media empire with legions of fans, will end its run in 2011 after 25 seasons on the air.

Holding back tears, the 55-year-old Winfrey told the audience at the end of a live broadcast of "The Oprah Winfrey Show" that "prayer and careful thought" led to her decision.

Winfrey said she loved the show, that it had been her life and that she knew when it was time to say goodbye. "Twenty-five years feels right in my bones and feels right in my spirit," she said.

Winfrey talked about being nervous when the programme began in 1986 and thanked audiences who had invited her into their homes and lives over the past two decades.

"I certainly never could have imagined the yellow brick road of blessings that have led me to this moment," she said.

Once a local Chicago morning programme, the production evolved into US television's top-rated talk show for more than two decades, airing in 145 countries worldwide and watched by an estimated 42 million viewers a week in the US alone.

"Oprah Winfrey is in a category of her own," said Robert Thompson, professor of television and popular culture at Syracuse University. "This is a great American story and like any great American story it's supersized."

Winfrey's talk show became the foundation for her multibillion-dollar media empire, Harpo Productions Inc., but in the last year, has seen its ratings slip seven percent. Winfrey is widely expected to start up a new cable television talk show on OWN: The Oprah Winfrey Network, a much-delayed joint venture with Discovery Communications Inc. that is projected to debut in 2011. OWN is to replace the Discovery Health Channel and will debut in some 74 million homes.

Winfrey offered no specifics about her plans for the future on yesterday's show, except to say that she intended to produce the best possible shows during her last 18 months on the air.

"Over this holiday break, my team and I will be brainstorming new ways that we can entertain you and inform you and uplift you when we return here in January," she said. "And then, season 25 — we are going to knock your socks off."

CBS Television Distribution, which distributes "The Oprah Winfrey Show" to more than 200 US markets, held out hope it could continue doing business with Winfrey, perhaps producing a new show out of its studios in Los Angeles.

"We know that anything she turns her hand to will be a great success," the CBS Corp. unit said in a statement. "We look forward to working with her for the next several years, and hopefully afterwards as well."

Many fans heading into Harpo Studios yesterday morning seemed to support Winfrey's decision to end the show.

"It's time to elevate to something new," said Sandra Donaldson, 59, of Indianapolis. "Whatever she does is going to be a blessing. It's going to be rewarding and eye-opening. Her name alone opens doors."

Audience members described the atmosphere inside the studio yesterday as tense and emotional, with some reaching for tissues as Winfrey announced her decision. "The whole audience was very quiet and she kept saying, 'You can breathe'," said Jennifer Aguilera, 32, of Joliet, Illinois.

Winfrey's 24th season opened this year with a bang, as she drew more than 20,000 fans to downtown Chicago for a block party with the Black Eyed Peas. She followed with a series of blockbuster interviews — Mike Tyson and Evander Holyfield, singer Whitney Houston and just this week, former Alaska governor and Republican vice presidential candidate Sarah Palin.

Her show's coverage has ranged from interviews with the world's celebrities to an honest discussion about Winfrey's weight struggles.

In 1986, pianist-showman Liberace gave his final TV interview to Winfrey, just six weeks before he died. In a 1993 prime-time special, Michael Jackson revealed he suffered from a skin condition that produces depigmentation. Tom Cruise enthusiastically declared his affection for the much-younger Katie Holmes on the programme in 2005 — and jumped on the studio's couch to prove it.

In 2004, Winfrey unveiled her most famous giveaway, when nearly 300 members of the studio audience opened a gift box to find the keys to a new car inside. The stunt became a classic show moment as much for Winfrey's reaction — "You get a car! You get a car! You get a car! Everybody gets a car!" — as its $7 million price tag.

The show also became a launching pad for Oprah's Book Club, which then launched best-sellers. The titles ranged from "Song of Solomon" and "Paradise" by African-American writer Toni Morrison to Holocaust survivor Elie Wiesel's "Night".

For others, the selection backfired. "A Million Little Pieces" exploded in sales after Winfrey chose the James Frey memoir in autumn 2005. Soon after, it was revealed as a fabricated tale of addiction and recovery, and Winfrey later chewed out Frey on her show.

The loss of "The Oprah Winfrey Show" would be a blow to CBS Corp., which earns a percentage of hefty licensing fees from TV stations that use it — largely ABC network affiliates. CBS chief executive Leslie Moonves told analysts two weeks ago that any negative impact won't hit the company until 2012.

Winfrey started her broadcasting career in Nashville, Tennessee, and Baltimore, Maryland, before relocating to Chicago in 1984 to host a local television station's morning talk show "A.M. Chicago" — which became "The Oprah Winfrey Show" one year later. She set up Harpo the following year and her talk show went into syndication.

Powered by the show's staggering success, Winfrey built a media empire. Harpo Studios produces shows hosted by Dr. Phil McGraw and celebrity chef Rachael Ray. O, The Oprah Magazine was the 7th most popular magazine in the US in the first half of 2009.

"I came from nothing," Winfrey wrote in the 1998 book "Journey to Beloved". "No power. No money. Not even my thoughts were my own. I had no free will. No voice. Now, I have the freedom, power, and will to speak to millions every day — having come from nowhere."

In 2003, Winfrey, who spent her earliest years in abject poverty in rural Mississippi in the then-segregated South, became the first African-American woman to make Forbes magazine's billionaire's list. Earlier this year, Forbes scored her net worth at $2.7 billion.

The Oprah Winfrey Leadership Academy for Girls, which cost her $40 million, opened near Johannesburg, South Africa, in 2007.