Rene Boucher entered the guilty plea in federal court in Bowling Green, Kentucky, to a charge of assaulting a member of Congress. Paul suffered broken ribs in the attack past year. Boucher faces up to 10 years in prison and a fine upwards of $250,000.
Special Judge Marianne Battani set Boucher's sentencing for June 15.
Paul was attacked November 3 while mowing his lawn at his home.
"He is looking forward to closure on all of this once and for all", said Boucher's attorney, Matt Baker.
Some residents of the gated neighbourhood in Bowling Green had speculated the attack was motivated by a dispute over yard debris. Baker says he'll argue for probation.
Boucher has agreed to pay an undisclosed amount to Paul as restitution.
Boucher, a retired anesthesiologist, said he tackled Paul from his blind side because he saw the senator stacking brush into an existing pile. Rand Paul while Paul was mowing his lawn.
Battani allowed Boucher to remain free on a $25,000 unsecured bond ahead of his sentencing, and ordered him not to have any contact with the senator or his family.
He also characterized the attack as a dispute that boiled over that had nothing to do with politics.
"The Pauls have had no conversations with him in many years", senior adviser Doug Stafford said last year.