34-year-old Rudolph Smith, of Frederick, was taken into custody on Monday after a 21-month long investigation, the Frederick Police Department said.
Authorities said they received a tip that Smith was actively having sexual relations with multiple women knowing that he was HIV positive.
Detectives said he was meeting the women on various dating websites and apps.
Smith has been indicted on four counts each of assault in the first degree, reckless endangerment and knowing transfer of HIV prohibited, Fox News report.
Detectives have identified and contacted several victims, but are urging anyone who may have had a sexual relationship with Smith around or after July 2017 to contact them.