Glen Reece Miller, 55, from Hunmanby, near Scarborough, was sentenced at Leeds Crown Court following a week-long trial.
His three victims were aged under 13 at the time of the offences.
Two boys from the Wakefield area of West Yorkshire were subjected to abuse between 1981 and 1985.
A boy from the Scarborough area became another victim in September 2014.
Miller denied all the offences, which included two counts of indecency with a child, the sexual assault of a child aged under 13 and four counts of indecent assault.
In sentencing him, the judge took into account previous offences against another five boys aged under 13 which occurred at Maidstone, Kent, in 1990 and at Walworth, south east London, in 1993.
He will now be subject to a lifelong sexual harm prevention order.
Det Con Sarah Walkey, of the Scarborough Serious Crime Team, said: “Miller’s abuse spans 35 years and the long prison sentence reflects his history of offending and the sheer gravity of his sickening crimes.
“I am satisfied that justice has been served for the victims in this case, and I have nothing but praise for their bravery in coming forward and providing the evidence needed to secure his conviction.”
DC Walkey added: “I hope the outcome of this case will give other victims of such abhorrent crimes the confidence to report it to the police and seek the professional support that is readily available.
“It is never too late to report this type of crime.”