Ashley Fisler, 36, of Washington Township, New Jersey, was arrested on Thursday.
The Gloucester County Prosecutor says Fisler had the alleged relationship with the student in 2021 while she was a teacher at Orchard Valley Middle School.
The victim, who is now an adult, reported the details to the police earlier this year.
Officials say Fisler is no longer employed as a teacher in Washington Township or anywhere else.
Fisler has been charged with six counts of first-degree sexual assault of a minor, one count of second-degree endangering the welfare of a child, and one count of second-degree official misconduct.