James Brian Rainford was previously convicted of battery against Hilton's former boyfriend Cy Waits, who was hit outside a courthouse in April.
In the latest incident, Rainford was arrested on the Fourth of July for allegedly staring into Hilton's Malibu home from a nearby beach.
Rainford appeared to be obsessed with Hilton and his alleged actions gave the hotel heiress good reason to be afraid, Superior Court Judge Jessica Silvers said.
"It's very clear from all these incidents that you are obsessed with Paris Hilton," Silvers told Rainford after a 90-minute hearing. "This is more personal, and it is scary."
Hilton did not appear in court on Monday.
Rainford is charged with two felony counts of stalking and three misdemeanor counts of disobeying a court order. He remains jailed and returns to court on August 29.
Rainford did not react after Silvers' ruling and only spoke quietly with his attorney during the hearing.
Defense attorney Craig Renetzky argued during the hearing that Rainford had never directly threatened Hilton, and the only thing he's ever done to her was propose to her at a book signing.
A trial date has not been set.
The Associated Press contributed to this report.