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 previous year.
The man accused of tackling U.S. Sen. The charge can carry up to ten years in prison as well as a hefty $250,000 fine.
A June 15 sentencing date for Boucher has been set, with federal prosecutors looking to give him a 21-month prison sentence.
Paul was attacked on 3 November 2017, while mowing his lawn at his home in Kentucky.
Boucher's attorney, Matt Baker, said he will ask for probation.
According to Associated Press, Boucher has agreed to pay restitution to Paul, but the amount will be confirmed during the sentencing later this year.
"He is anticipating acquiring an entire determination", Baker said.
The case, which has been characterized as a property dispute between neighbors in the Rivergreen subdivision where the two men live, made national headlines in the wake of Boucher's arrest and provided fodder for late-night talk shows.
The 59-year-old Boucher has admitted to tackling Paul from behind as he mowed his lawn last November.
In a plea agreement, Boucher said the incident wasn't motivated by politics, but rather a property dispute that had "boiled over".
Boucher was released on a $25,000 unsecured bond on Friday and is not allowed to contact Paul or his family.