Mark Richard Davis, 55, gained the trust of lone mothers to get close to boys and "dazzled" them with tricks before abusing them, Cardiff Crown Court heard.
The crimes came to light after three men told police they had been abused by him in the 1980s and 1990s in Cardiff.
Davis, from Corby, Northamptonshire, was found guilty of 13 sex offences.
Janet McDonald, prosecuting, said during his week-long trial Davis, also known as Mark Major, was a "skilled groomer" and "sexual predator" who targeted boys from fatherless homes.
He had worked both as a children's entertainer and was involved in youth theatre.
Ms McDonald said he "wormed his way" into the boys' lives. He promised them trips to London to visit the set of the EastEnders TV programme and gave them autographed pictures of celebrities, the court was told.
Davis was found guilty of three counts of rape, nine indecent assaults and one charge of taking an indecent photograph of a child.
At a sentencing hearing on Friday, Judge Jonathan Furness told Davis: "You enticed them with the lure of the theatre and the magic of your role as an entertainer.
"You befriended them and their families. They were vulnerable due to their circumstances. You were a father figure.
"They have experienced long lasting effects through their lives and have suffered for many years because of the memories of your abuse."
After the hearing, Det Insp Dan Michel, from South Wales Police, said Davis, also known as Mark Major, abused his links to youth organisations across the UK and his position of trust as a children's entertainer.
"The victims have shown tremendous courage to come forward and tell us about the abuse they suffered," he said.
"We know reporting these crimes of this nature can be difficult, but we would urge anyone who has been a victim to report it to us, you will be supported."
A former Cardiff magician has been jailed for 14 years for historical sex abuse on schoolboys.