Bishop Gatimu Ngandu Girls High School, popularly known as BG or BeeGee, was founded in 1960 by Bishop Caesar Gatimu in Ngandu area of Mathira Constituency in Nyeri County, Kenya. It was first named "Ngandu Girls' High School" for the area where it was situated. The name was later changed to honour its founder, The Right Reverend Caesar Gatimu. It was originally run by the Comboni mission. Sister Sr Alexandrina was the first Principal then Sister Nazarena Zonta and her deputy, SisterSr Lucilla. Sbicego ran the school until 1983. Lay headmistresses, now principals in the employment of the Teachers Service Commission have headed the school since. The First Native Principal was Ms. Helen Wathuti Waweru-Hsc who served as Principal from 1983-2006, The immediate past Principal is Ms Virginia Wahome, who was promoted to The Kenya High School in January 2023.[1], the current Principal is Ms.Jane Kimiti from 2023. The school's alumnae group, ONGA (Old Ngandu Girls Association) - Started in 1987 by Ms.Helen Waweru who was a student at the school from 1966 -1969 - unites alumnae to help revamp the school and collect donations. The association, which is registered with the Registrar of Societies, visits the school to talk to the student body and offer them career advice and leadership.[2] ONGA is chaired by Hellen Muyumbu (Class of 1999).
The school motto is "Empowering to Serve".