Oprah is expected to make the announcement on-air on Friday during "The Oprah Winfrey Show," which airs at 9 a.m. on ABC 7.
The last show will be on September 9, 2011.
ABC7's Cheryl Burton asked Oprah whether she planned to continue her show after the 25th season during a Michigan Avenue appearance with Ellen Degeneres on November 6.
"It is the big question of the day, Cheryl, and something I have to answer soon," said Oprah.
It all started back in January of 1984 when the girl from Kosesko, Mississipi began hosting AM Chicago here on Channel 7.Then one year later it became "The Oprah Winfrey Show."
Over the years, the queen of talk has interviewed countless celebrities and just ordinary citizens.
The talk show was just one entity of the Harpo empire which includes radio and publishing.
Nine years ago she unveiled O Magazine.Oprah has graced every cover since except two times when her rival Ellen Degeneres and First Lady Michelle Obama joined her.
Recently, Oprah went to Copenhagen to convince the International Olympic Committee that Chicago should host the 2016 Games.
"This city has never failed me. I could cry when I think about this city," said Oprah.
The Oprah Winfrey Show will not move to her new cable channel, the Oprah Winfrey Network based in southern California.
ABC7 has learned that Oprah has no plans to move to California herself at least through September of 2011.
Chicago reacts to Oprah announcement
As word of her decision to end the show began to spread on Thursday night among Oprah fans, reaction was immediate.
At the Wishbone Restaurant across from Harpo Studios fans could hardly believe it.
"It's sad to see her go but I know she'll do something better," said Lindsay Wilcox, Oprah Fan.
"I don't believe it. Maybe it is because I don't want to believe it. I think it is a negotiation ploy.," said Raymond Lambert, Oprah fan.
The Oprah Winfrey Show attracts about 7 million television viewers a day. But the show means so much more to the city of Chicago in terms of visibility and marketing the city. And Oprah's association with the city is considered by many to be one of Chicago's most valuable assets. She was one of the biggest drawing cards as part of the delegation that recently went to Copenhagen to pitch Chicago for the 2016 Olympics.
"Oprah means a lot to everyone," said Cheryl Denise Williams, Oprah fan.
Harpo Studios also employs several hundred Chicagoans and anchors a revitalized near West Side area of development.
Mayor Daley heard the news after her company released it to the media on Thursday night.
"I'll talk to her because she has huge real estate holdings on the West Side," said Daley.
The show is also a major tourist attraction. Those fortunate enough to get tickets to the taping of her show come from all over the country and the world. The economic impact is in the tens of millions of dollars.
"She is a Chicago icon on the level of a Michael Jordan. What that means to Chicago is for 25 years, a lot of eyeballs on our city and you can't put a price tag on that," said Jerry Roper, Chicagoland Chamber of Commerce.
No media is allowed into Friday morning's show and Oprah does not plan to do any interviews. After the show, she goes on hiatus until January.