"I'm here to admit that I am in fact HIV positive," he told Lauer. "I have to put a stop on this onslaught, this barrage of attacks, and of sub-truths and very harmful and mercurial stories that are about the threatening the health of so many others, which couldn't be farther from the truth."
Sheen, 50, said that he discovered that he was HIV positive about four years ago after he suffered excessive sweating and a series of debilitating headaches.
"I thought I had a brain tumor. I thought it was over," he admitted. "It's a hard three letters to absorb. It's a turning point in one's life."
Sheen added that he was paying money to individuals he once thought were his friends to keep them quiet about his condition. By going public with the news, he said, "I release myself from this prison today."
The actor also said that has been open about his status with every person with whom he's been intimate since his diagnosis. Now, he hopes his openness will help others.
"I have a responsibility now to better myself and to help a lot of other people," he said. "Hopefully with what we're doing today, others may come forward and say, 'Thanks Charlie. Thanks for kicking the door open.'"
Sheen has been an A-list star for more than 30 years, starring in classics like "Wall Street," Platoon" and "Major League." But it was the actor's off-screen relationships and antics that often took center stage. Sheen won a Golden Globe Award for his role on the hit show, "Two and a Half Men." But in early 2011, around the time of his diagnosis, the series was put on hiatus after Sheen entered rehab following several days of heavy partying. ("I wish In the weeks that followed, Sheen went on a public tirade against Chuck Lorre, the show’s creator, and was barred from the set. He was fired shortly thereafter. People magazine reported at the time that a letter from the producers to Sheen’s attorney said the actor "engaged in dangerously self-destructive behavior" and "failed to continue with his rehabilitation program."
Sheen made his TV comeback on FX's "Anger Management" in 2012. The show was cancelled last year. Since then, Sheen has remained out of the spotlight.
Along with his feud with Lorre, Sheen has had several tumultuous relationships, including three divorces with ex-wives Donna Peele, Denise Richards and Brooke Mueller. Most recently, Sheen was engaged to adult film star Brett Rossi, but the two broke it off late last year.
Rossi wasn't the first adult actress Sheen publicly dated. After his split from Mueller, the actor was living with his "goddesses," as he called them, including actress Bree Olson. In the 1990s he was also linked to other adult stars.
Sheen is the father of five children -- daughter Cassandra, 30, from a relationship in the 1980s, two daughters Sam, 11, and Lola, 10, with Richards, and 6-year-old twin sons, Bob and Max, with Mueller.