Kitui High School is a boys' boarding secondary school in Kitui County and the only national boys' secondary school in the county. It has a population of 1,500 students. It is located about 2 kilometers from Kitui town along the Kitui-Mbusyani road.

Kitui School began as an intermediate school in 1908 before changing to a boarding school in 1948. The school was by that time known as Campbell Academy. It started offering A-level classes in 1971.

1°22′22″S 38°00′14″E / 1.372775°S 38.003891°E / -1.372775; 38.003891