The centre, designed by Taylor Architects in association with Richard Murphy, won the Public Choice Award at the annual RIAI Irish Architecture Awards.
It is the second time in five years that Taylor Architects has taken the top prize. The centre was one of 60 projects on the shortlist and all were designed by RIAI-registered architects.
More than 14,000 people voted online for a building of their choice, and over 20% chose the winning project.
Second place went to the Central Bank of Ireland at Dublin’s North Wall Quay, originally intended to be Anglo Irish Bank’s headquarters.
In third place was a Cork project — Child’s Play Tower, designed by architect Neil Kane for his daughter, Ailbhe.
RIAI president Carole Pollard said the tree house was a project of passion that captured the public’s imagination.
“The architect said his six-year-old daughter was as demanding as any corporate client could be,” said Ms Pollard.
Speaking on RTÉ radio, Ms Pollard recalled that Ailbhe wanted the tree house to be painted yellow, not pink.
“It looks like a simple structure but is actually very sophisticated in its design,” said Ms Pollard.
She said the new Central Bank building was probably the most public building in Ireland.
She said the concrete frame that had stood by the quay for so long a represented all that was rotten at the core of Ireland’s financial collapse.
The building was designed by Henry J Lyons Architects. Ms Pollard said they took the “concrete skeleton” and clad it using the highest technology of office construction.
She said the O’Donoghue Centre was the overall winner by “a long shot”.
The protected structure was a bleach and flax mill in the 1850s and had also served as a munitions factory.
More recently it had been used as the college’s engineering laboratories before the construction of the new engineering building.
The centre is a 120-seat theatre space and allows for multifunctional use and accessibility. There are studio spaces, a classroom, a workshop and a rehearsal room.
It has received generous philanthropic support from Galway businessman, Donagh O’Donoghue who graduated from the university with an Arts and Business degree in the 1960s.
Ms Pollard said while there was a great selection of projects this year — areas that were missing were multiple housing schemes and social housing and that needed to change.