The service will remember the first responders, families and survivors caught up in the terror attack at London Bridge earlier this month.
Dean of Southwark, the Very Revd Andrew Nunn, said: "Southwark Cathedral was at the heart of the terrible events of that Saturday evening.
"Now reopened we seek to be a place of healing, reconciliation, rebuilding and hope for the whole community.
"We are praying that through these services and in other ways we can begin to do that."
Bishop of Southwark Rt Rev Christopher Chessun will lead the service.
Eight people died with around 50 injured when three terrorists drove a van at pedestrians on London Bridge before leaving the car and attacking people with knives at Borough Market.
Friday's event will be a private gathering but a further service at Southwark Cathedral for the community to join together and commemorate these events will take place on Friday 23 June at 2pm