Armstrong was light on the details and didn't name other names in an interview that aired Thursday night on the Oprah Winfrey Network. But he answered "yes" to all five of the following questions:
- "Did you ever take banned substances to enhance your cycling performance?
- "Was one of those banned substances EPO?
- "Did you ever blood dope or use blood transfusions to enhance your cycling performance?
- "Did you ever use any other banned substances like testosterone, cortisone or human growth hormones?
- "In all seven of your Tour de France victories, did you ever take banned substances or blood dope?"
The disgraced cyclist admitted taking part in an elaborate doping scheme and took responsibility for the cover-up.
"My cocktail, so to speak, was only EPO, not a lot, transfusions and testosterone," said Armstrong. "All the fault and all the blame here falls on me."
Armstrong told Winfrey that he never felt he was cheating and that he was just leveling the playing field.
"I view this situation as one big lie that I repeated a lot of times," he said. "I know the truth. The truth isn't what was out there. The truth isn't what I said."
Armstrong's decade of deception hurt many, like his former teammate Frankie Andreu, who says he was targeted for threatening to expose Armstrong's cheating.
Winfrey showed tapes of Armstrong's aggressive denials through the years and explained how he often set his lawyers on old friends or colleagues that accused him of doping.
"You're suing people and you know they're telling the truth?" Winfrey said. "What is that?"
"It's a major flaw," Armstrong answered.
Armstrong called himself "a flawed character." He added that there are people who will hear his confession and never forgive him, and he said he understands that. There were no tears, no pleading for sympathy.
Armstrong's admission now carries risk. Part two of his interview, which airs Friday night, will be closely watched by lawyers. His lies under oath have outlasted the statute of limitations for criminal perjury. But he could face several civil lawsuits.
As for why he chose now to disclose the truth, Armstrong said he had no real answer.
The Associated Press contributed to this report.