Christopher Angelo Manzo, 22, was arrested at his firefighter job.
Manzo allegedly prearranged a meeting with the teen - who investigators described as under the age of 16 - in Greensboro's Bur-Mil Park last month.
Investigators said park officials learned of the meeting last week and reported it to authorities.
Manzo - a Pittsboro resident - is charged with statutory sex offense and two counts of indecent liberties with a minor.
Bond was set at $150,000.
Wake County Public School System confirmed Manzo has worked for the district as a substitute in the past. It was gathering more information in his tenure.
The Town of Cary said it was investigating the facts surrounding Manzo's arrest and would determine the appropriate steps it would take.