James 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."
Rainford, 36, was previously convicted of battery against Hilton's former boyfriend Cy Waits, who was hit in the head outside a courthouse earlier this year.
Rainford did not react after Silvers' ruling and only spoke quietly with his attorney during the hearing.
Rainford's most recent arrest came after a July 4 encounter in which paparazzi alerted authorities he was outside the heiress' beach house.
Defense attorney Craig Renetzky argued during the hearing that Rainford had never directly threatened Hilton, and that she had never left her home during either incident that led to his arrests.
His actions, including hitting Hilton's ex-boyfriend and shoving a security guard in October, were not directed at the socialite herself, the lawyer said.
"The only thing he's apparently ever done to her is to propose to her," Renetzky said.
Hilton politely refused. She did not attend Monday's hearing.
Prosecutor Wendy Segall called four law enforcement officers to testify about their dealings with Rainford after his arrests or their conversations with Hilton.
Sheriff's Detective Rodney Wagner said Hilton was "afraid for her safety as well as her family, her friends around her."
Rainford remained jailed in lieu of $150,000 bail and was told to return to court on Aug. 29 for an arraignment. No trial date has been set.