The school was started in 1976 as Harambee Mixed Day Secondary School. This was a local community initiative, as many of the local children lacked places in the government schools, which were only two at that time.
The late Hon. Njenga Karume and Dr. Gachathi, when approached, kindly supported the initiative by giving financial assistance for the construction of classes on a seven-acre piece of public land where the school currently stands. The school was then named after him in his honour.
The school started as a single-streamed school and was affiliated to the then St. Mary’s Boys Primary School, where the first batch of students were admitted in Form One. The first head teacher was Mr. Nango. Later the school gained its current status, moved to the current compound, became a government public school, and has grown into a six-streamed school.
