Robert McGeachy, 64, was jailed for eight years in June 2024 after being found guilty of 17 charges at the High Court in Glasgow the previous month.
The Crown Office and Procurator Fiscal Service asked the court to consider imposing a longer custodial term due to the serious nature of the offences.
The Appeal Court upheld the Crown appeal. The original sentence has been quashed and replaced with a 12-year custodial term.
While sentence is rightfully the domain of the independent judiciary, the balance of justice is served by the Crown being allowed to appeal in limited circumstances.
The Appeal Court has set a high test to be satisfied for this to happen.
The sentence must be unduly lenient, meaning it falls outside the range of sentences which the judge could reasonably have considered appropriate having taken account of all relevant factors.
Kenny Donnelly, Deputy Crown Agent for the Crown Office and Procurator Fiscal Service, said:
“COPFS is committed to improving the criminal justice journey for victims, from the stage of reporting all the way through to sentencing.
“Prosecutors have a responsibility in legislation to consider appeals based upon undue leniency in sentencing.
"Such appeals are rare but important to ensure the public interest is properly served.
"They allow the court to review sentences that the Crown believe fall outside the range of punishment reasonably considered appropriate.
"COPFS believes that it is important that the harm caused by sexual offending, and the culpability of the convicted person, must be consistently reflected in sentencing decisions.”
McGeachy’s campaign of physical and sexual abuse took place at various addresses in the Glasgow area between 1978 and 2003.
He sexually abused several young children as well as raping a teenager and a woman.