Callum Lewis, 20, of Gemel Road, Burton Pidsea, was sentenced at Hull Crown Court on Friday after a jury found him guilty of 15 child sex offences, including sexual activity with a child and possession of indecent images.
The court heard how Lewis contacted his victims on social media sites, manipulating them into feeling sorry for him and forcing them into receiving obscene images or sending indecent images.
Humberside Police said in some cases he would take them in his car to spots where they would be “isolated and unable to get away from him”.
The force said they applied for a sexual risk order after receiving reports about the 20-year-old, which allowed them to carry out inquiries while keeping a “watchful eye” on him.
They worked with West Yorkshire Police after he moved out of the area so the neighbouring force could continue monitoring him while their inquiries progressed.
Lewis was caught breaching his court bail conditions twice by trying to obtain further indecent images and was remanded in custody last October.
Det Con Nicola Gibbs, from Humberside Police, who led the case, praised the “incredibly brave” victims for coming forward. She said because of the manipulation that had taken place during his offending, some of the girls were not even even aware they were victims.
She said: “I understand that for victims of sexual abuse, no matter the outcome, something like this will always live with them. However, I do hope now the investigation has drawn to a close and Callum Lewis is behind bars, they feel some sort of closure.”
The sentencing came after a trial which ended in early March.
He was found guilty of seven counts of causing or inciting a child to engage in sexual activity, three of sexual activity with a child, two of taking indecent photographs and three of possessing indecent photographs.