Jurors found Rahman guilty of the offences, which included two counts of rape, seven counts of indecent assault and four counts of sexual intercourse with a child.
Police said the victims came forward to report the offences in December 2022 and an investigation was opened by Rotherham’s child exploitation team.
Det Con Rachel Watts, the officer in charge of the case, said: “Rahman preyed on two vulnerable young girls, subjecting them to years of horrific abuse.
“I would like to commend the tremendous bravery of both victims, who had to re-live the abhorrent crimes during the trial as a result of Rahman refusing to admit what he had done.
“Their courage has resulted in Rahman now likely to spend the rest of his life behind bars.”