Principal Rob Dickson said the project's completion marked the end of a lot of hard work and was a significant event in the school's history.

"It means Creswick families will be assured of facilities that are among the best in the state for many years to come," Mr Dickson said.

"Of course we are very grateful to State and Federal governments for their funding," he said.

The project saw four temporary classrooms replaced with first-class administration and classrooms, and an adjoining gallery.

Assistant principal Aileen Dellar said Mr Dickson had been instrumental in gaining funding for the project.

"Mr Dickson has thanked a lot of people for help with this project but, for something like this to happen you need a strong leader and Mr Dickson has definitely give us that," Mrs Dellar said.

School historian Wendy Ohlsen was pleased the extensions retained the building's historic features.

"The works are great and they have really modernised the buildings without destroying the heritage of school.

"The upgrades will mean this building will remain here for at least another 100 years," Mrs Ohlsen said.

The Federal Government committed $600,000 to the development and the State Government contributed $916,000.

Hepburn Shire councillor and former school council president Janine Booth said the school deserved the upgrade.

"As a parent of three students at this school, I know our school has a great spirit," Cr Booth said.

"It was like another place when I walked in here today," she said.

On opening the second stage of the project, Ballarat East MLA Geoff Howard said the entire Creswick community would benefit from the development.

The construction of a multi-purpose building in 2004 was part of the upgrade's first stage.

"Creswick Primary School is now a leader in school infrastructure across the state," Mr Howard said.

The first school at the Creswick site was built in 1874 and hadn't been significantly upgraded in since.

Ballarat East MHR Catherine King was also a guest at the opening. Mayor David Smith, Education Minister Bronwyn Pike were apologies.