The 40-year-old has been fighting since he was formally charged in June. He continues to claim his innocence but says he is is weary of the legal fight, according to a statement released on Thursday.
"The toll this has taken on my family, and my work for our foundation and on me leads me to where I am today – finished with this nonsense," Armstrong said.
The USADA has now declared that it is set to ban Armstrong from cycling for life and strip him of the seven consecutive Tour de France titles he won between 1999 and 2005, according to a report in the BBC.
The anti-doping agency has alleged that Armstrong took banned substances as far back as 1996, including steroids, blood transfusions and the blood-booster EPO.
Armstrong had until 8am CET on Friday to declare whether he intended to continue to contest the charges, but has elected to end the fight to clear his name.
He has previously sued in a federal court to block the charges but lost.
"If I thought for one moment that by participating in USADA’s process, I could confront these allegations in a fair setting and – once and for all – put these charges to rest," Armstrong wrote.
"But I refuse to participate in a process that is so one-sided and unfair."
But the USADA has said that ten of Armstrong's former teammates have pledged to testify against him and accused him of being a "ring-leader" of systematic doping in the teams which he represented.
The former cyclist turned triathlete has meanwhile pointed out that he never failed a drugs test during his active career.
Armstrong survived testicular cancer before embarking on his Tour de France winning streak.
He retired after his seventh tour win in 2005, but returned to compete for a further two years in 2009.