Armstrong addressed the staff and said: "I'm sorry." He choked up and several employees cried during the session, the source, someone who has knowledge of the situation said.
Armstrong apologised for letting the staff down and putting Livestrong at risk but he did not make a direct confession to the group about using banned drugs. He said he would try to restore the foundation's reputation.
Armstrong urged the group to continue fighting for the charity's mission of helping cancer patients and their families.
After the meeting, Armstrong, his legal team and close advisers gathered at a central hotel in Austin, Texas, for the interview. The seven times, Tour de France winner gave what was described as a "no-holds barred," 90-minute, interview to Ms Winfrey. The cyclist apologised and made a limited confession about his role as the head of a long-running scheme to dominate the prestigious bike race with the aid of performance-enhancing drugs, according to a well-placed source.
Ms Winfrey and her crew filmed the interview at Armstrong's home in Texas and it will be broadcast on Thursday on the Oprah Winfrey Network. If he was feeling any pressure, Armstrong hardly showed it during a jog under bright skies, even as members of his legal team began arriving one by one at his home.
"I'm calm, I'm at ease and ready to speak candidly," he said, but declined to reveal how he would answer questions about the scandal that has shadowed his career. He was stripped of all his seven Tour titles last year in the wake of a voluminous US Anti-Doping Agency report that portrayed him as a ruthless competitor, willing to go to any lengths to win the prestigious race.
USADA chief executive Travis Tygart labelled the doping regimen allegedly carried out by the US Postal Service team that Armstrong once led as "the most sophisticated, professionalised and successful doping programme that sport has ever seen". The interview was Armstrong's first public response to the USADA report. Armstrong is not expected to provide a detailed account about his involvement, nor address indepth many of the specific allegations.
He has revealed in advance of the programme that: "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."
After a federal investigation of the cyclist was dropped without charges being brought last year, USADA stepped in.