In part two tonight, Armstrong talks about his personal life and the effect his lying has had and might have on his legacy, including the Livestrong charity he founded.
Executives have weighed on Armstrong's confessional.
Livestrong CEO Doug Ulman said, "There was a little sense of relief because our organization today can finally move beyond this topic and this issue."
During the interview, Armstrong told Winfrey, "I viewed this situation as one big lie that I repeated a lot of times."
For sure, Armstrong's admission dominated sports talk radio.
There's also reaction from those Armstrong attacked for attacking him. Former teammate Tyler Hamilton was forgiving but not forgetful.
"It's a huge, huge step for Lance Armstrong, big first step it's really what happens next the proof is in the pudding," Hamilton said.
The interview could get expensive for Armstrong. Sponsors and those he sued over the years are already lining up to recover what they paid him.
Following a report in October by the US Anti-Doping Agency, Armstrong was stripped of his seven Tour de France titles. On Thursday, the International Olympic Committee also took away Armstrong's bronze medal he won at the 2000 Sydney Olympics.