The Brimstone missile system is to be fitted to the Royal Air Force's latest drone, the Protector.
It will enhance the ability of the drone, also known as the MQ-9B SkyGuardian, to target high-speed, moving targets.
Since first being used by the RAF in June 2009, the weapon has been used extensively in Afghanistan, Libya and most recently Iraq and Syria.
It will now be fitted to the new Protector RG Mk1 drone.
Arriving in the UK for the first time at RAF Fairford last summer, the Protector builds on the design success of the existing reaper drone system.
Britain is to have 20 Protector drones – and the installation of the Brimstone missile builds on work trialled on the Reaper.
Protector will become fully certified to fly missions from RAF Waddington, the base already responsible for operating the Reaper aircraft, raising the possibility of drone bombing runs starting from this country.
Speaking last year, Air Marshal Julian Young said: "There are no unmanned aircraft that are able to fly in densely populated areas over the United Kingdom or over Europe.
"This aircraft, with our ambition of fully certifying it through the Military Aviation Authority, will allow us to do exactly that."
The Brimstone missile will be attached to the Protector in pods of three.
There are seven weapons stations on the drone, meaning a total of 21 Brimstone missiles could be carried.
It means a significant uplift over Reaper, which could carry four Hellfire missiles or two 500-pound laser-guided bombs.
Britain is increasingly using weaponised drones in operations.
Reaper fired 258 hellfire missiles against so-called Islamic State targets in 2015.
The addition of Brimstone to the newer drone variants will enable them to tackle faster moving, smaller targets.