The gaol was built by prisoners who slept on high security barges on Corio Bay during construction. The three-storey central block is cruciform with east and west wings serving as cells, the north wing as an administration block, and the southern wing as a kitchen, hospital and a tailoring workshop. The Australian Army used the prison as a detention barracks during, and for a few years after, World War II.
The government closed the gaol in 1991 and the Rotary Club of Geelong now operates it as a public service project. It is open to the public on Saturdays, Sundays and daily during public and school holidays. The gaol remains mostly unchanged. A gallows exhibit recreates the 1863 hanging of James Murphy, who battered Constable Daniel O'Boyle to death at the Warrnamboolcourt house. He was the last person hanged at the gaol. Cell 47 is of special interest as it contains a mural painted on a wall by a prisoner, titled Window of Freedom.
The Gaol is now referred to as the "Old Geelong Gaol". Some believe the gaol may be haunted and several paranormal research groups have visited the site.