First opened in 1877 under the name HMP Kingston, it closed down in March 2013.
The site in Milton Road has now been acquired by renowned developers St Cross Homes and work is underway to to convert it into residential homes, with the first phase set to be completed in autumn 2021.
The main prison building and gatehouse are being transformed into a 83 beautiful apartments, ranging from one to three bedrooms, all with an allocated parking space.
You can now look inside a two bedroom apartment on sale at the Old Portsmouth Gaol for £215,000.
The pictures show how inside the flats, the rooms are very comfortable with warm décor and look very different from the prison days.
In fact you might even find it hard to believe the apartments even used to be part of a jail!
You can subscribe here for unlimited access to our online coverage, including Pompey, for 27p a day.