Mosocho Academy was a primary boys' boarding school admitting pupils from standard Three to Eight. In 1989, the school expanded to include the secondary wing which admitted its first batch of students in forms One and Two that year.
In 1992, when the first Kenya Certificate of Secondary Education examination was sat, the school emerged as a top-twenty best in the country. From then, the schools attracted students from all over the country and beyond. Good performance continued for a time until in 1996. Decline in academic standards visited the school immediately after the death of the proprietor Dr Hon Z. T. Onyonka in 1996. However, inept financial and academic leadership drove it to almost financial ruin. It was bought in 2001, after the death of Onyonka, by an educational entrepreneur of Indian origin.
The school has undergone several changes, it stopped admitting boarding students and became a mixed secondary school.
Head teachers
Upon inception, the school was headed by Mr Otwoma from 1986 to 1988. Otwoma left the school to work with the Gestetner company in early 1989. He was succeeded by Mr. D. A. Mokoro from 1989 to 1991.He was demoralized as his dream to be sponsored to study in the United States did not materialize. He resigned to go back to the Teachers Service Commission (TSC) for redeployment. Mokoro was a teacher at Kabianga High School before he got official release by the TSC to join Mosocho Academy. He started the secondary wing and taught religious studies in that section. Thereafter, he joined the University of Nairobi where he graduated with a B.Ed (Hons) degree before proceeding to Kenyatta University from where he earned his master's degree in Educational Planning and Economics of Education.
In 1992, the schools were headed by Mr. Francis Gichana who was a retiree from the TSC and a close neighbor to Dr Onyonka. 1991 was marked by the repeal of section 2a of the constitution of Kenya and the reintroduction of multiparty politics. The son of Mr Gichana (Dennis Gichana) was involved in these politics and chose to oppose the then incumbent Onyonka in Kitutu Chache constituency in the 1992 general elections.