The 39-year-old American, who rode alongside Armstrong in each of his seven Tour de France wins, released a statement on Wednesday confessing that he cheated.
"Because of my love for the sport, the contributions I feel I have made to it, and the amount the sport of cycling has given to me over the years, it is extremely difficult today to acknowledge that during a part of my career I used banned substances," he said.
"Early in my professional career, it became clear to me that, given the widespread use of performance enhancing drugs by cyclists at the top of the profession, it was not possible to compete at the highest level without them."
Hincapie, regarded as Armstrong's unofficial lieutenant during his record breaking feats in the Tour de France from 1999 to 2005, joined a list of former Armstrong teammates, including Floyd Landis and Tyler Hamilton, to admit to doping.
The three were among 11 riders identified on Wednesday as having provided evidence to the United States Anti-Doping Agency (USADA) in its investigation into doping in cycling.
Armstrong has always denied using drugs but was banned for life in August after deciding not to fight the charges laid against him by USADA.
Hincapie said he stopped using drugs six years ago and decided to come clean about his own past in a bid to restore credibility to the sport.
"Two years ago, I was approached by US Federal investigators, and more recently by USADA, and asked to tell of my personal experience in these matters," he said.
"I would have been much more comfortable talking only about myself, but understood that I was obligated to tell the truth about everything I knew. So that is what I did.
"Cycling has made remarkable gains over the past several years and can serve as a good example for other sports," Hicapie said.
"Thankfully, the use of performance enhancing drugs is no longer embedded in the culture of our sport, and younger riders are not faced with the same choice we had."
- Tour de France