Museum curator Nigel How said the "heartwarming" turnout was bigger than he expected.
Kiwa Hammond of Te Reinga Marae addressed the crowd in the main foyer and reflected on his role as a "mouthpiece" for the descendants pictured on the walls of the museum.
"What better way to learn about ourselves than to learn about our past," he said.
A wall in the museum reads that this conflict is 'as relevant today as it was then' and conflict is a strong theme for the museum's archives.
A Pai Mārire flag returned from Scotland hung in the main foyer as a centrepiece for the museum.
Its historical significance was marked on Christmas Day in 1865 when 200 troops attacked the small village of Omaruhakeke; it was likely to have been one of the flags surrendered.
After a New Zealander found this flag in Scotland it made its final voyage back to Wairoa where it now rests in a glass case.
Museum director Mike Spedding spoke highly of the education the archives would provide whanau, particularly the younger generation.
"Education is a priority and we hope that the museum will unlock taonga and korero," he said.
Along with education programmes for schoolchildren, Mr Spedding announced the curation of informational books that will be sent out to local schools.
Wairoa Deputy Mayor Denise Eaglesome-Karekare said the newly-renovated museum will "absolutely" benefit the Wairoa community.