Up until now staff have been split across two Masterton locations.
Rental income from the building is returned to the Masterton community through Lands Trust grants.
"Today marks the start of a new era for a significant property that has served our community well and will continue to do so," said Lands Trust Masterton deputy chair John Bunny, following Monday's dawn blessing of the new building by local kaumatua which was attended by around 40 staff and guests.
"We warmly welcome our new tenants and extend our thanks to all the contractors, 16 of them local to Wairarapa, who worked so hard to produce such a magnificent community asset."
Wise Group joint chief executive Julie Nelson said they were pleased to partner with Lands Trust Masterton to ensure the building was purpose-designed.
"It is our belief that the Wairarapa community will come to see this space, and the people working within it, as a wonderful resource for the health and wellbeing of the region," he said.
The name 'Waiata House' recognises the Opera House's musical history and its logo reflects the old building's arched windows which were salvaged and incorporated into the new building. Decorative corbels from the Opera House and floorboards from the former St Patrick's school have also been placed.