Timaru's first court sittings were held in the 1850s in the Custom House building. In 1864 new court offices consisting of seven rooms were built. There were three rooms for the Magistrate's Court, two for Public Works and two for the Survey Department. At the time this build was being constructed it was recognised that the space provided was insufficient and that a larger building was needed to hold the Magistrate's and Supreme Courts. The government was responsible for provision of a plan and William Clayton, Colonial Architect, drew the plans for Timaru. Tenders for a new courthouse were called in 1876 and then again in March 1877.

Before construction began the Timaru Herald (9 March, 1877) commented on the design:

The new courthouse for Timaru will be a striking piece of architecture, and it seems to be well designed for the purposes for which it will be used... Its greatest width will be 75 feet and depth 59 feet. The portion of the building to be used for the Court will be 49 feet long and 25 feet wide, standing end-on to the street, and there will be wings on each side providing the necessary small rooms... In the wings are to be rooms for the judge, the jury, the lawyers, the witnesses, the registrar, and the public; and the fire proof safe is to be situated in one of the wings... The interior of the building will be plastered and a dado will extend along each wall four feet high.. In the front elevation of the Courtroom will be three fine circular headed windows...and the margins of these will be stained glass. The building will be in concrete, with a slate roof, and the ornamentation will be in cement.

The new building was constructed on the site of the former court offices, taking nearly a year to finish and opening on the 4th March 1878. On the building's completion there was considerable criticism of its design and the unsuitability of the internal planning. The height of the judge's seat obscured his view of the jury, the acoustics were defective and the chimneys smoked badly. Efforts to correct these problems were only partly successful but the building continued in its original form until the 1950s when alterations and additions were made. In 1974 when the building had been in use for 96 years it was indicated that it was time for it to be replaced. However, further alterations and additions along the street frontage were made in 1978, securing the building's future for an extended time. Additions to the North Street frontage were made again in 1983 and the building continues its original use today.

Despite the 1978 additions which have altered the Victorian character of the single storeyed street frontage, the building still makes a major contribution to the streetscape. The courthouse section rises above the flanking wings. Notable features are the roof lantern, the gable detailing and the three arched windows featuring keystones and the quoins.