The announcement is also cause to celebrate for the Thousand Stars members who make regular contributions towards the redevelopment.
Oscar Toy, 12, is one of the youngest contributors, donating $5 a week for the past two years, and he is now at the $500 halfway mark.
He has been visiting the Sarjeant from an early age, and his parents were married under the central dome.
"I really enjoy art, especially abstract art. I think it's a very good thing to be giving money to such an important part of Whanganui culture," Oscar said.
His memories of the Sarjeant as a 9-year-old are of walking down wide hallways "and it was really big".
He is keen to see the changes that the renovations, earthquake strengthening and new extension will bring. He will be 15 when it is completed.
"I'm expecting it to be a lot more modern in its design, and there will be more artworks on show. There is a massive collection," he said.
In the exhibition, Oscar is drawn to Peter Ireland's wide angle Queen's Park Panorama - "it's really big and nice looking. There are ghostly figures painted on top of it and you can see the road that leads up to the Sarjeant."
He also likes the embossed, abstract work by Rodney Fumpston.
"It's such an iconic building, you can't but help notice its shape when you see it."
He is happy to have made the "active decision" on his own to contribute to a building that will be standing proud when he is much older.
"It means somehow I've helped recreate an [important] landmark for the city - something that's recognisable, that's always been there, [so that] when you think of it you think Whanganui."
Jaki Arthur, the new relationships officer at the Sarjeant, says she has been amazed and touched by the amount of support for the redevelopment through the Thousand Stars initiative which allows people to contribute $5 a week if they choose.
"Seeing the level of rock solid community support via the Thousand Stars program makes me love Whanganui even more.
"There are so many actively supporting the gallery by giving regularly and quietly.
"Now is the time to be a part of the redevelopment and to watch it happen.
"The Thousand Stars people will all be recognised in the redeveloped building so it really is a chance to be a part of Whanganui's history.
"We hope that more people will sign up"