Thornell Earl Thomas, 38, of Seminole Heights, traveled from Tampa to meet a Largo girl, who is under 18 for sex, according to Largo Police.
Parents of the girl, who is not being named because of the nature of the incident, called police after seeing Thomas sitting in his car near a neighbor's house around 7 p.m. Aug. 14, according to arrest records.
Thomas first lied about why he was in the area, police said. He then said he was there to meet the girl, who he claimed he thought was over 18.
However, the girl said that he knew otherwise.
They met through the online dating service waplog.com, according to investigators.
Thomas admitted to using the online chat service to meet women for sexual encounters, according to police. He said he was unaware that he needed to register his account.
Thomas was using two online chat accounts that he failed to register with Florida Department of Law Enforcement and the Hillsborough County Sheriff's Office, as required by law.
Thomas already is on probation for a lewd and lascivious battery conviction and possession of cocaine.
Thomas was arrested and charged with two counts of failing to register email or instant message account, traveling to meet a minor and three counts of violation of probation. He is in jail awaiting trial on $150,000 bond.