Kevin Humphries, from Worcester, had his 18-month sentence referred to the Court of Appeal under the Unduly Lenient Sentence scheme.
Humphries now 60, was in his early 30s when he indecently assaulted two teenage boys in separate incidents.
Humphries knew his victims and pleaded guilty to two counts of indecent assault in October 2022 at Worcester Crown Court after one of the victims alerted the police in 2020.
The offender was given a sentence of 18 months' imprisonment at Hereford Crown Court and given a sexual harm prevention order.
Following the sentencing on 22 November 2022, the case was referred to the Court of Appeal under the Unduly Lenient Sentence scheme.
Humphries' original sentence was found to be unduly lenient by the court on 15 February 2023 and was increased to two years and six months.
Speaking after the hearing, the Solicitor General Michael Tomlinson KC MP said:
Kevin Humphries enticed two teenage boys with adult appropriate gifts before he abused their trust and carried out his sickening assaults.
The impact on his victims' lives has been great and an increased sentence for Kevin Humphries shows that this appalling behaviour will not be accepted.
