Terry Williamson, perpetrator of 11 appalling crimes two decades ago, has been freed by a parole board in Sydney this morning.

At a hearing in Parramatta, the NSW State Parole Authority granted the convicted rapist parole after more than 20 years behind bars, the Illawarra Mercury reports.

Williamson, 42, will leave Silverwater Correctional Centre between February 10 and 17.

The parole board imposed a range of strict conditions including electronic monitoring, regular drug and alcohol testing and a ban on visiting the Illawarra and contacting his victims.

Williamson must also undergo a psychiatric evaluation.

The former Corrimal man's maximum sentence expires in 2014 but he has been eligible to apply for early release since 2004.

Since that time a number of parole applications had been rejected upon advice from the Serious Offenders Review Council - until now.

Families across the Illawarra, particularly in Wollongong's northern suburbs, lived in fear during Williamson's nine-month terror campaign.

As a 20-year-old, Williamson kidnapped, raped and sexually assaulted 11 victims, including children as young as five.

He preyed on women and children and frequently attacked victims inside their homes.