Oprah Winfrey reacts to the crowd as she starts a taping celebrating the 24th season of The Oprah Winfrey Show in Chicago September 8, 2009. The show airs on September 10. REUTERS/Frank Polich

Oprah Winfrey, one of the most influential and highly paid women on television, will announce on Friday she is ending her popular daytime talk show in 2011.

Winfrey's production company, Harpo Inc, said on Thursday she would make the official announcement on Friday's live program from Chicago and talk about the reasons behind the decision to end it after 25 years on the air.

She is expected to move to cable network OWN, or Oprah Winfrey Network, a Los Angeles-based joint venture she formed with Discovery Communications Inc, when her current syndication deal for The Oprah Winfrey Show runs out in 2011. OWN will be available in more than 70 million homes.

Harpo declined to comment on whether or when a revised form of the program might appear on OWN, whose launch has been delayed several times since its original 2009 start date.

The Oprah Winfrey Show, broadcast from Chicago on ABC stations across the United States and in more than 140 countries overseas, is one of the TV industry's biggest money-makers. It is the top-rated U.S. daytime talk show, averaging 7.1 million viewers this year.

Winfrey, 55, is considered a major opinion-maker in the United States and this year was No. 45 on Forbes magazine's list of the world's most powerful people.

She publicly promoted Barack Obama during his 2008 presidential campaign and her program became a platform this week for Republican 2008 vice presidential candidate Sarah Palin to launch her book, Going Rogue.

Actor Tom Cruise, the late Michael Jackson, and singer Whitney Houston are among the celebrities to have sat on, jumped on and poured out their hearts on her couch since the program began in 1986.

Winfrey used the show to launch her magazine, a book club that turned authors into best-sellers, and a cable TV channel, Oxygen, geared to female and lifestyle topics.

Her decision will affect CBS Corp's CBS Television Distribution arm, which syndicates the show, and Walt Disney Co's ABC-owned and operated TV stations that broadcast the show.

CBS TV Distribution said in a statement it wished Winfrey well. We have the greatest respect for Oprah and wish her nothing but the best in her future endeavors. We know that anything she turns her hand to will be a great success. We look forward to working with her for the next several years, and hopefully afterward as well, the statement said.