[1] The first borough council offices in Oamaru were in a wooden building on the south side of the Thames Street Bridge, occupied since the 1860s, but by the turn of the century were considered too small for hosting civic events, as well as being "old and unsightly".

[1] Builders Winsley and Sons were contracted to construct the building for £10,600, although the design was then altered to include both a second storey and a concert hall.

[1] According to conservation architect Chris Cochran the building ‘is a significant example nationally of the Edwardian Baroque style, a bold and assertive design that proclaims the prosperity and pride of the town of Oamaru...The design significance is particularly evident in the interior – particularly the Proscenium arch, circle, council chambers, and the plaster ceilings in the theatre circle.

[1] The building was registered by the New Zealand Historic Places Trust as a Category I item in December 1993, with registration number 7356.

Besides a complete range of civic functions, the Opera House has hosted theatre, ballet, concerts, cinema and boxing.