The move comes as joint production of the vehicles by the UK and Germany begins in Telford, Stockport, and Munich.
Following the expansion, the British Army will now receive a total of 623 Boxer Mechanised Infantry Vehicles (MIV).
The overall procurement includes multiple variants of the vehicle including infantry carriers, specialist carriers, command vehicles, and ambulances.
The production has already started, with the first vehicles expected to arrive next year.
The first 117 vehicles are being manufactured in Germany while the remaining 506 units will be made in UK facilities in Telford, and Stockport.
Commenting on the UK-German ties, British Prime Minister Boris Johnson said: “In these difficult times, our deep defence partnership offers reassurance to our people, and the wider world, while also ensuring we are ready to respond to new threats.
“This joint programme will ensure our militaries have state-of-the-art equipment as the invasion of Ukraine shakes the very foundations of European peace and security.”
UK Defence Procurement Minister Jeremy Quin said: “This order will accelerate the delivery of the Boxer fleet to the British Army, and increase its numbers.
“The land equipment upgrade is a vital element of the integrated review, on which we continue to deliver. Doing so, alongside our German allies, creates opportunities for both our Armed Forces.”
Earlier this year, Nasmyth Group secured a contract to supply precision machined and fabricated components for British Boxer MIVs.