The courthouse at Opotiki reflects the town's historical role as a centre for the administration of law and order in the eastern Bay of Plenty. It is also linked with the ongoing improvement of government facilities following New Zealand's establishment as a Dominion in 1907. Built in 1910-1911, the timber building was erected on the corner of Church and Elliott Streets, the main crossroads in the settlement. The structure replaced an 1870s courthouse on the same site, which was part of a group of government buildings - including a post office and police station - that were rebuilt in the years immediately after 1910. The courthouse occupied the most prominent position of these buildings and was the first to be replaced.

As one of the most pre-eminent government buildings in Opotiki, the courthouse symbolised the presence and authority of government rule. The administration of government, and law and order in particular, was a significant issue in Opotiki, whose foundation as a military and commercial settlement in the 1860s had occurred on confiscated Te Whakatohea land. Erected at least partly as a result of local pressure, the courthouse was built not only shortly after New Zealand's Dominion status was achieved, but at the same time that civic government for the town was cemented. Opotiki was constituted as a borough in 1911, when its population was just over 1,000 inhabitants. The building fulfilled functions other than those connected with the judicial system, including the registration of births, deaths and marriages. The site had an important association with the first establishment of local government in the eastern Bay of Plenty, as a meeting in the previous courthouse in 1877 had founded the Whakatane County Council.

The courthouse was erected as a single-storey weatherboard structure, with a courtroom, judge's chamber, offices, and a strong room towards the rear. It was constructed at an initial cost of £1,073 under contract to C. M. Grant of Opotiki. Designed by the Public Works Department headed by John Campbell, the building incorporated influences from domestic architecture, including elements of transitional bungalow style. These included a low-pitch roof with cross gables, exposed rafters, and mouldings under the windows. Nevertheless, the scale of the courthouse and aspects such as the logo 'GR' ('George Rex', or King George V) above the main door, made it evident that it was a government building. The restrained ornamentation was part of a trend seen in other courthouses designed by John Campbell in the 1910s. This can be seen as displaying a more 'democratic' approach to the appearance of some government architecture in the years following the establishment of the Dominion. A strong influence from domestic architecture on the design of provincial courthouses was a common theme in northern New Zealand, extending back into the nineteenth century.

Although the building was formally opened in February 1911, additions were made using day labour by 1912. A long outbuilding to the rear may have been erected partly as a coach house, and was being used as a garage by 1948. For much of the century, prisoners were brought to the courtroom from a lock-up behind the police station next door. Following the closure of the station, a cell block wing was added to the courthouse in 1997. Earlier modifications included relocating the courtroom to the southern side of the building, partly to improve the waiting facilities and create additional office space. The structure avoided the fate of many small courthouses in the 1990s, when many were closed, and remains in regular use by the Department for Courts.

The courthouse at Opotiki is a well-preserved example of small-town judicial architecture from the early 1900s, still being used for its original purpose. It is linked with the improvement of the administrative infrastructure of New Zealand in the early years of the Dominion (1907-1947), and the architectural work of John Campbell. The building demonstrates Opotiki's administrative role in the Bay of Plenty region, and is believed to be the earliest purpose-built government building in the town to survive in its original location. It retains elements, such as an original safe, that are directly related to its early judicial and administrative functions. Located on the site of an earlier courthouse, its position directly reflects mid nineteenth-century ideas about the layout of new military and commercial settlements. The building adds to the streetscape and distinctive character of Opotiki, being located on a prominent corner. It is part of a valuable historical urban landscape of nineteenth and early-twentieth century date, which contains other heritage buildings, including the nearby Masonic Hotel and War Memorial.