Hincapie, who turns 39 on June 29, announced his decision in a statement Monday.
The affable, understated Hincapie was a longtime aide for Lance Armstrong during the mountain stages of the Tour de France, helping him win each of his seven titles. He helped Alberto Contador win the Tour in 2007 and Cadel Evans win the iconic stage race last summer.
He's expected to help Evans defend his title when the Tour de France starts June 30 in Liege, Belgium. Now riding for BMC Racing Team, Hincapie would be riding his 17th Tour de France, breaking the record he had shared with Dutch rider Joop Zoetemelk for the most starts in history.
"I came to the conclusion that I want to go out while I can still contribute and make a difference," Hincapie said. "To be able to compete for 19 years as a professional cyclist has been something I would have never dreamed of doing. But at the same time, it's also going to be good to spend more time with my kids, who are getting to be the age where they miss me when I'm gone." Hincapie made his first Olympic team at the 1992 Barcelona Games. He's been a part of the U.S. team for every Olympics since, and will learn by Monday whether he will be chosen as part of the road team that will compete in London this summer.
While he's most well known for being a faithful servant to other riders -- in cycling, the term is domestique -- Hincapie has achieved no shortage of personal milestones.
He's won several stages in the Tour de France, and has been a constant threat in cycling's spring classics, winning Gent-Wevelgem in 2001 and finishing second at Paris-Roubaix in 2005. He's also won Three Days of De Panne and the Tour of Missouri during nearly two decades of racing.
Hincapie won national road race titles in 1998, 2006 and 2009.
"I am very proud that he was able to start as a professional with me on the Motorola team in 1994 and that I'm still with him at the end of his career," said Jim Ochowicz, the president of BMC Racing Team. "It's been an honor to bookend the career of one of the nicest people and one of the greatest cyclists America has ever produced." Hincapie has mostly escaped the specter of doping that has shadowed many riders of his era, including Armstrong, who remains one of his close friends.
The most serious accusation against Hincapie came in May 2011, when "60 Minutes" reported that he told federal authorities that he and Armstrong supplied each other with performance-enhancing drugs and discussed them. Hincapie has said he never spoke to "60 Minutes" and didn't know where it got its information, and otherwise declined to discuss the report.
Hincapie said he will remain involved with cycling, perhaps even with the BMC Racing Team. He'll also be busy with his company, Hincapie Sportswear, which has grown into a leader in performance apparel targeted primarily at cyclists.
"I'm hoping that he'll change his mind, probably like many other cycling fans around the world will do when they hear the news," said Evans, who is fresh off a third-place victory in the Criterium du Dauphine, his last major prep before his Tour de France defense.
"George is incredible," Evans said. "He's the core of the BMC Racing Team, and not just on the road as a captain, but also in the structure of the team. He's a part of so many aspects of everything we do because of his tremendous leadership." Hincapie was quick to point out that there is plenty or racing left this season.
"I want to see it grow while putting in more time with the people I love, but also know that I'm still feeling strong and healthy and ready to make a contribution to the team these last two months," Hincapie said. "I'm 100 percent motivated to help Cadel win another Tour."