37°49′42″S 144°45′8″E Port Phillip Prison is a maximum security prison located at Truganina, Victoria, Australia. It is Victoria's largest maximum security prison, able to accommodate up to 1117 prisoners.^[2] The prison is privately operated on behalf of the Government of Victoria by G4S Australia Pty Ltd.^[3]

Originally cited to be called Metropolitan Men's Prison the facility was renamed prior to its opening to Port Phillip Prison.^[4] The facility was the third privately operated prison to open in Victoria. It received its first prisoners on 10 September 1997.^[2]

G4S confirmed that a prison officer resigned in April 2016 after 100 weapons were seized from his home by Victoria Police as part of an ongoing investigation into firearms offences.^[5]

In 2022, a 16 year old boy was held in maximum security for almost four months, against advice from the sentencing judge, during which time he was routinely held in isolation and confined to his cell for 23 hours a day.^[6]

The prison consists of 13 accommodation units including a youth unit named Penhyn for young adult inmates aged 18–25 who are first time offenders only with no criminal record. All other under 25 prisoners are sent to mainstream units. The induction unit named Matilda is divided into 2 and all prisoners spend time there before being located to other accommodation units. Cells within the units have a shower, hand basin, toilet, desk, chair, television, storage shelves, intercom and bed.^[3]

The prison operates a 20-bed inpatient hospital unit.^[3]

• Julian Knight, perpetrator of the 1987 Hoddle Street massacre.
• Jason Joseph Roberts, convicted of the Silk-Miller police murders.^[7][8]
• Paul Denyer, the "Frankston Serial Killer".
• Blair Cottrell, Chairman of the United Patriots Front, convicted of stalking and arson.^[9]
• Peter Dupas, convicted serial killer.