David Timmins, of Hunters Drive, Gringley-on-the-Hill, was found guilty of four counts of indecent assault, one count of indecency with a child and two counts of rape on Monday, following an 11-day trial.
The 66-year-old was arrested in September 2015 after the victims reported what had happened to them, however he denied the offences.
Timmins, the court heard, offered the girls cigarettes, abused them and told them not to tell anyone.
Detective Constable Greg Evans, of Nottinghamshire Police, said: “This has been a very lengthy investigation and the victims have shown great strength in bringing it to court and seeing justice done.
“We are pleased with the sentence. Timmins is a nasty individual who needed to be held to account for his actions two decades ago.
“I hope this sends the message out that these cases will be investigated to the best of our ability as it’s vital that victims continue to come forward no matter how long ago the abuse took place.
“We will not tolerate the sexual abuse of children in Nottinghamshire.”
As well as the prison sentence, Timmins will have to sign the sex offenders register for life and was given a Sexual Harm Prevention Order which prevents him from living with anyone under the age of 18 and from having any contact with the victims.