The University of Edinburgh building making the shortlist was previously a Category A listed Victorian hospital.
Bennetts Associates repaired and remodelled the facility for Edinburgh Futures Institute to include a 450-seat auditorium, teaching and social spaces, and a new public square.
Judges said the “transformative” works “preserved the integrity of the historic building yet created a modern, welcoming, clever, and stimulating place that people want to work in and return to”.
RIAS president Libby Heathcote, who was one of the judges, said making the shortlist was a challenge because of the “exceptional calibre” of the eligible buildings this year.
“The three chosen projects are testament to the quality, innovation and rich diversity of building design in Scotland,” she said.
“All three tap into important, current conversations around community, collaboration, retrofit and reuse across three very different contexts.”
The judges will visit each building in person before making a final decision.