The teacher, Paul Harris, had sex with student at her home, and the relationship still continues.
Mr Harris, who taught at an unnamed school, was banned by a professional conduct panel of the Teaching Regulation Agency in a ruling in which it said a lifetime ban was the only appropriate sanction.
The panel noted the relationship between the two began in October 2017 and still continues.
Sex at former student's home
Mr Harris admitted the clandestine sexual relationship began within two to three months of the student leaving school after he provided her with his personal contact details.
They concealed the relationship from colleagues, Mr Harris' wife and the students’ parents.
The panel noted: “The relationship began and continued despite Mr Harris' recently prior position of authority over [the] pupil as one of her teachers. The imbalance in the dynamic of their relationship remained, given Mr Harris' very recent position of trust over [her].
“The serious misconduct took place outside of the education setting but clearly amounted to behaviour that could have led to pupils being exposed to or influenced by Mr Harris's behaviour in a harmful way.”
It said public confidence in the profession “could be seriously weakened if conduct such as that found against Mr Harris were not treated with the utmost seriousness when regulating the conduct of the profession”.
The panel said there was no mitigating factor other than Mr Harris’ previously good record and it found a lifetime ban was appropriate, a recommendation agreed by Department for Education decision-maker Alan Meyrick.