The Thistle Weir Youth Academy was established in October 2013 when the Weirs provided an initial £750,000 to get it running to the end of 2016.
The academy has already achieved a top five place in the national under 17s league, four star status with Club Academy Scotland and the progression of three Academy players into the first team set up.
And the Thistle Weir Ladies team, now part of the Academy set up, are currently top of their league.
Now the Weirs are providing an extra £500,000 to ensure it continues to progress.
Thistle chairman David Beattie, said: “The development across the Thistle Weir Youth Academy in recent years has been nothing short of phenomenal.
“Youth development is a massive part of the club’s long term future and is something that the club sees as essential to underpinning further success.
“Although a long term project, we are already starting to reap the rewards from the initial investment as players break through to the first team.
“Huge credit has to go to Gerry Britton and Scott Allison, along with their dedicated team, for building that infrastructure from virtually nothing.
“There’s no two ways about it, the Thistle Weir Youth Academy is absolutely massive for this club and we are grateful to Chris and Colin for this further generous donation.”
On extending the funding, Colin Weir said: “We are delighted by what the Academy has achieved to date.
“Gerry and his team have made impressive progress in a relatively short time, so we are very happy to provide further funds to ensure the Academy continues to grow.”