The contract extension will allow the ship to remain in the South Atlantic to protect the Falklands Islands until 2018.
HMS Clyde is a highly flexible platform with a displacement capacity of 1,847t that can cruise at a speed of 21kt with a crew of 43 members.
The ship has been designed to replace HMS Leeds Castle and HMS Dumbarton Castle and will remain permanently in the Falklands.
The offshore patrol vessel features air defence radar, versatile flight deck and helicopter-in-flight-refuelling capability.
BAE Surface Ships division managing director Mick Ord said the contract will help the UK Ministry of Defence to reduce costs and deliver maximum availability of warships to meet operational commitments.