The refurbishment has cost £9.7 million and is part of £600 million invested in research and teaching facilities.
Brand-new studios, offices, workshops and a state-of-the-art exhibition hall have been added to the Bute Building.
The additions have modernised the building that was designed by Sir Percy Thomas and will bring the entirety of the Welsh School of Architecture (WSA) back under one roof.
Larger, lighter and more flexible studio spaces have been designed alongside a renovated interior and the roof has been ugraded and repaired.
Workshop facilities have also been relocated and expanded with an enlarged wood and metal workshop, digital fabrication facilities to produce models using laser cutting, 3D printing and CNC (Computer Numeric Control) technologies, and an enhanced space for the WSA’s robotic arm.
An exhibition space and Living Lab have been created at the front of the building, and the original two-storey assembly hall has been uncovered and reinstated.
The exhibition hall, which opened last month, will be the centrepiece of the building.
Dr Juliet Davis, head of the Welsh School of Architecture said: “I am absolutely delighted to be able to showcase the building to the public and to officially mark the start of a new era for the Welsh School of Architecture.
“The Bute Building has been our home since our inception in 1920, and so this is the perfect way for us to celebrate more than 100 years of existence.
“As the adaptation of an historic building, this refurbishment embodies the School’s long-held ethos of sustainability.
“We hope it will foster creativity and collaboration, incubating new ways of thinking, researching, learning, writing and making architecture for decades to come.”
Alongside the refurbishment, new postgraduate taught and undergraduate programmes are being offered.
Global design practice BDP’s Cardiff studio were the project architects for this work.
Nick Durham, architect director at BDP in Cardiff and graduate and former tutor on the Masters degree course at the WSA, said: “It has been a privilege to play a part in shaping the future of this historic building where generations of architects have been and will continue to be supported and inspired for many more decades to come.
“Key to our approach was the intelligent and sensitive repurposing of the building, based on a thorough understanding of the original Sir Percy Thomas design.
“This has helped ensure that our new interventions work with the building fabric to deliver flexible and sustainable learning environments based on the future needs of the school.”