Joseph Smith, 37, used his position of trust to prey on the girls from for more than four years until he was arrested in June 2019.
West Midlands Police said Smith had been living in Wolverhampton when he began his abuse of the first girl by sexual touching, before raping her. The abuse continued for several years until the girl found the courage to report what was happening to her.
After detectives from the force's Public Protection Unit began an investigation into what happened, it emerged that Smith had also abused a second girl by sexually assaulting her.
Smith then denied the charges and forced both survivors to endure a two-week trial at Wolverhampton Crown Court which ended on November 24 when the jury found him guilty of nine counts of sexual assault and nine counts of rape.
On Thursday Smith, most recently of Wiltshire, was sentenced by a judge to 24 years in prison and will remain on the Sex Offenders Register for life.
Detective Constable Kerry Bromhall, of the unit, said: “Smith subjected the girls to years of physical abuse, not to mention the psychological torment that such abuse often leaves behind.
“I commend these young girls for their bravery, firstly in coming forward to report what happened to them, but also in continually reliving their experience through a lengthy investigation, hampered by Covid, and giving evidence at trial.
“I truly hope this sentence gives them the closure they need and the knowledge that Smith is no longer able to do this to anyone else.”
The force added that anyone who has been subjected to sexual abuse, no matter how long ago will be listened to by specialist officers.