Michael O'Brien, 48, taught at the Christopher Columbus Charter School. Administrators immediately fired him after learning about the allegations.
He was taken into custody on Aug. 30.
The victim is a 16-year-old girl and was previously taught by O'Brien at the K-8 school.
Police say the abuse happened multiple times in 2024, including in mid-July.
The affidavit states O'Brien engaged in sexual communication with the girl.
Investigators also allege he was soliciting naked images of the teen and sending naked images of himself to her.
Police also say he engaged in sexual intercourse with the girl over various dates.
Action News went to O'Brien's home in Brewerytown for comment, but no one was home.
The district says all faculty members, including Mr. O'Brien, are required to pass strict protocols before being hired, including criminal background checks by the FBI.
He had taught at the school since 2021.
"Our thoughts and prayers go out to the young woman identified as the victim in this matter," the school said in a statement.
O'Brien is not allowed to have any unsupervised contact with minors.
The school district says it will provide counseling services for all students, families, faculty and staff who request support in the days ahead.