Pasadena police say they arrested 33-year-old Charles Pearson on Wednesday after Pinsky notified them of threats received by him and his family.
Jail records show Pearson is being held on $150,000 bail.
Police say Pearson is suspected of posting threats online about Pinsky and showed up at a Los Angeles radio station recently.
Pinsky is an addiction specialist who hosts the radio show "Loveline" on Los Angeles' KROQ 106.7. He also hosts several VH1 reality shows, including "Celebrity Rehab."
Jail records do not indicate whether Pearson has an attorney.