The suspect was arrested by the Shomolu division of the Child Protection Agency (CPA) after neighbours who witnessed the incident raised an alarm.
During interrogation, the victim revealed that the suspect had been sleeping with her in the past any time his wife was out of the house.
The 17-year-old explained that she confided in two other neighbours about how the cleric defiles her but they didn't believe her story.
Mustapha, who hails from Ilorin, Kwara State, met his day of reckoning after he was caught red-handed in the act on February 16.
During interrogation, the 38-year-old, who had initially denied the act, opened up that he only had carnal knowledge with the girl once not thrice as she alleged.