David Wicks, 55, who formerly lived in Swindon, pleaded guilty to nine counts of indecent assault on the girls who were both aged between 14 and 15 years of age at the time of the offences which took place at Wyvern Theatre in Swindon.
It is understood he worked as technical manager at the Waterside Theatre from 2010 to 2014.
ATG, who run The Waterside Theatre said: “ATG is aware of a recent court case regarding a former employee at the Aylesbury Waterside Theatre.
“We can confirm that the person in question was dismissed as a result of gross misconduct on a matter unconnected to the court case.
“The dismissal was handled in accordance with ATG policies and procedures.”
The Swindon incidents took place between July 1996 and July 1997 with one girl, and between January 1999 and January 2001 with the other girl.
Wicks was also put on the Sex Offenders Register and given a Sexual Offences Prevention Order for life.
Following the sentencing on August 23 at Swindon Crown Court Det Con Mike Armishaw from Swindon CID said: “I want to highlight the bravery of the victims who came forward after all these years, who had the full confidence to stand up and give evidence against David Wicks with the support of the police and the criminal justice system.
“I hope this sentence gives them some form of closure so they are able to move on with their lives.
“For years David Wicks worked at the Wyvern Theatre, and during the Summer Youth Projects he was able to identify young vulnerable girls, prey on them and ultimately go on to abuse them.
“His pattern of offending demonstrated that he was able to manipulate situations to his advantage and was extremely calculated in doing so.
“David Wicks’ guilty plea reflects the overwhelming level of evidence that he was faced with.”
The court heard how Wicks sexually abused the girls, on separate occasions years apart, in the changing rooms.
He also abused the second child at his home.
Wicks, now of Westergate, near Chichester, West Sussex, pleaded guilty to nine counts of indecent assault when he appeared at Swindon Crown Court.
Between July 1995 and July 1997 he kissed and molested a girl aged 14 or 15 in at least four occasions.
Then from January 1999 to January 2001 he carried out similar activities on another girl at the theatre on more than ten occasions and then at his home.
The court heard he had no previous convictions but was dismissed from a job in 2014 for gross misconduct over sexual advances to an adult female.
Wicks must register as a sex offender for life and will also have to abide by a sexual harm prevention order.