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.

This article needs additional citations for verification. (April 2023)

Kitui School began as an intermediate school in 1908 before changing to a boarding school in 1948.^[1] The school was by that time known as Campbell Academy. It started offering A-level classes in 1971.

• Willy Mutunga, Retired Chief Justice of Kenya
• Kalonzo Musyoka, 10th Vice-President of Kenya
• Makau Mutua, Former Dean of the University of Buffalo Law School
• John Ndirangu, Former Embakasi Central MP
• Ngumbau Mulwa, Mumias Sugar Company Limited director
• George Kenyatta Muumbo, Presidential candidate in Kenyan general election, 2013
• Ngala Mwendwa, A member of the Kenyan delegation to the 1960 Lancaster House Conference
• Muthomi Njuki, Governor Tharaka Nithi County and former Chuka-Igambang'ombe MP (taught Biology and coached rugby)
• Benjamin Nzimbi, Retired Archbishop and Primate of the Anglican Church of Kenya