Kangemi High School started in 1974 on the compound of the present day Ruthimitu Mixed Secondary School. It was started by the area member of Parliament Hon. A. Njoroge Mungai. Dr. Njoroge Mungai was responsible for starting other schools in Dagoretti constituency among them Mutuini Mixed High School, Ruthimitu Secondary. In line with problems the country faced on attaining Independence, disease, ignorance and poverty, education was seen as a weapon to help fight these vices. The Harambee movements which was introduced by the country's founding president Mzee Jomo Kenyatta who called upon the citizenry to join together to help get the country develop. The impending reasons caused the wave of starting several schools then. In 1974, the school moved from the compound of Ruthimitu Mixed Secondary School to the compound of Kangemi Primary where tuition was carried out in the former wood and domestic workshop of the Kangemi Intermediate school built in 1957. The first headmaster of the school was Mr. Upendra who later moved to Ruthimitu Mixed Secondary School leaving the school in the able hands of Mr. Kariuki Nguku. A board established in 1974 led by Mr. Hezron Kamau Waweru opened a new school bank account at the Barclays Bank Westlands and requested the City Council of Nairobi to approve plans for permanent structures. At the same time the board put up more timber classes to accomodate more students. The school board of governors set up a building committee made up of non-board members led by Hon. Francis Kahendi, the area Member of Parliament who was elected to parliament after the demise of Dr. Muthiora. Professor P.M Gitu was another prominent member in the committee. The committee with the help of the school board organized the first school's harambee with the following as Chief Guests; Mr. James Murioki Njogu, Mr. Lucas Ritho Ndungu and Mr. David Kamau Thiong'o. Funds raised in this harambee built the first phase of the school with the roofing contract awarded to Timsales Company and the City Council of Nairobi inspected the work for free. At around this time the school was informed of the existence of a dormant bank account in the name of the school at the bank of Baroda. Led by Mr. A.R.S Nzano the then school headmaster approached Dr. Njoroge Mungai to Release the money in the account totaling to Kshs. 74,000. This money was used to put up the first science laboratory.

Kangemi High School started in 1974 on the compound of the present day Ruthimitu Mixed Secondary School. It was started by the area member of Parliament Hon. A. Njoroge Mungai. Dr. Njoroge Mungai was responsible for starting other schools in Dagoretti constituency among them Mutuini Mixed High School, Ruthimitu Secondary. In line with problems the country faced on attaining Independence, disease, ignorance and poverty, education was seen as a weapon to help fight these vices. The Harambee movements which was introduced by the country's founding president Mzee Jomo Kenyatta who called upon the citizenry to join together to help get the country develop. The impending reasons caused the wave of starting several schools then. In 1974, the school moved from the compound of Ruthimitu Mixed Secondary School to the compound of Kangemi Primary where tuition was carried out in the former wood and domestic workshop of the Kangemi Intermediate school built in 1957. The first headmaster of the school was Mr. Upendra who later moved to Ruthimitu Mixed Secondary School leaving the school in the able hands of Mr. Kariuki Nguku. A board established in 1974 led by Mr. Hezron Kamau Waweru opened a new school bank account at the Barclays Bank Westlands and requested the City Council of Nairobi to approve plans for permanent structures. At the same time the board put up more timber classes to accomodate more students. The school board of governors set up a building committee made up of non-board members led by Hon. Francis Kahendi, the area Member of Parliament who was elected to parliament after the demise of Dr. Muthiora. Professor P.M Gitu was another prominent member in the committee. The committee with the help of the school board organized the first school's harambee with the following as Chief Guests; Mr. James Murioki Njogu, Mr. Lucas Ritho Ndungu and Mr. David Kamau Thiong'o. Funds raised in this harambee built the first phase of the school with the roofing contract awarded to Timsales Company and the City Council of Nairobi inspected the work for free. At around this time the school was informed of the existence of a dormant bank account in the name of the school at the bank of Baroda. Led by Mr. A.R.S Nzano the then school headmaster approached Dr. Njoroge Mungai to Release the money in the account totaling to Kshs. 74,000. This money was used to put up the first science laboratory.