According to an anonymous source, the retired cyclist will also apologize during the interview, which is scheduled to be taped Monday at his home in Austin.
In information released Saturday, the Associated Press said Armstrong sent the newsgathering organization a text message claiming he plans to be unequivocally honest and answer all of Oprah's queries.
"I told her (Winfrey) to go wherever she wants and I'll answer the questions directly, honestly and candidly. That's all I can say," Armstrong said.
The 41-year-old has never spoken publically about the doping allegations that cost him his seven Tour de France titles and barred him for life from competing in Olympic sports.
Armstrong's confession comes at a time where he's found himself entangled in legal trouble.
The former seven-time Tour de France champion is facing a federal whistle-blower lawsuit filed by former teammate Floyd Landis accusing him of defrauding the U.S. Postal Service.
The Sunday Times is also suing Armstrong to recover about $500,000 the British newspaper paid the cyclist after losing a libel lawsuit regarding doping allegations.
A Dallas promotions firm has threatened to sue Armstrong for allegedly lying under oath. The company is demanding the repayment of more than $7.5 million it paid the cyclist as a bonus for winning the Tour de France.
According to the statue of limitations, Armstrong is not subject to criminal perjury charges stemming from his sworn testimony denying doping in 2005.
Despite having lost most of his sponsorships including his contract with Nike and the Livestrong cancer-fighting charity, Armstrong is still said to be worth an estimated $100 million.
By confessing, the cyclist could be hoping to convince WADA and U.S. Anti-Doping officials to restore his eligibility and athletic career.
Armstrong met with officials recently to explore a "pathway to redemption," according to a report by "60 Minutes Sports" aired Wednesday on Showtime.
The interview will be broadcast Thursday on the Oprah Winfrey Network and oprah.com.
The Associated Press contributed to this report.