William King was convicted of three charges against two girls and a boy at the High Court in Stirling last month.
The 57-year-old attacked one girl on various occasions between 1982 and 1986 in Edinburgh.
He began assaulting another when she was just seven years old.
The jury heard he threatened a young boy while he sexually assaulted him at an address in Fife.
The offences took place between 1982 and 2000.At the High Court in Glasgow today, King was sentenced to six years in prison.
Procurator Fiscal for High Court Sexual Offences Fraser Gibson said:
“William King’s victims demonstrated great bravery and composure throughout the prosecution process and I hope the sentence imposed today provides some resolution for them.
“He was brought to justice thanks to a thorough and complex investigation by police and our expert prosecutors.
“The Crown is committed to the fair and effective prosecution of sexual offences, whenever the crimes occurred, and I would encourage anyone who has been the victim of similar offending to come forward and seek support.”