Armstrong finished third in the Tour last year, racing for the Kazakhstan-backed Astana team behind winner Alberto Contador in his return after a three-year absence. Armstrong won the Tour seven straight times from 1999- 2005 before retiring.
"And yes, this will be (my) final Tour de France. It's been a great ride," Armstrong posted on his official Twitter website. "Looking forward to 3 great weeks."
Following a rift with Contador, Armstrong started a team sponsored by RadioShack, the second-largest US electronics chain, for this year’s race.
