As a distinctive and worthy aspiration of the late educators Ricardo and Marcela Bonilla, the institution was established as the first private school in Malvar, Batangas in June 1947. The school was then an extension of Golden Gate Colleges located in Batangas City. The founders were dedicated to serve Malvareños in line of education. Starting with the first year level classes were held at the rented house along the Malvar national highway.
To cope with the increasing number of enrollees, after the school was granted permit to operate from first year to third year level, it transferred to a bigger area still along the Malvar national highway. At the time, after the students finished the third year level, they were sent to Lipa City Colleges, Lipa City, a sister school, for their fourth year level.
In 1961, the school was not anymore an extension of Golden Gate Colleges and was named after one of the Batangas heroes, General Miguel Malvar, so named General Malvar High School.
Determined to continue serving the educational needs of the people of Malvar, the founders acquired their own lot where the school now stands at P. Montecer St., Poblacion, Malvar, Batangas. The continuous success reaped by the only private secondary school in Malvar includes the awarding by the Department of Education in July 01,1968, the Government Recognition to General Malvar High School to be fully operational for complete secondary course.
The remarkable endeavor of the late Ricardo and Marcela Bonilla could be gleaned from the good number of enrollees up to the present and the successful graduates of General Malvar High School. Today, the General Malvar High School is renamed as Southgate Institute of Malvar, headed by Glecy B. Mojares, assisted by her daughter Beverly Mendoza, Vice President for Finance and Internal Affairs, her son-in-law Patrick D. Mendoza, Vice President for Administration and Corporate Affairs, Dr. Marjorie M. Abiera and Dr. Joe Vincent J. Abiera as consultants.
The remarkable endeavour of its founder passed through the generations as they kept dreaming for more improvement of the school. In 2017, Southgate was granted its application to offer Nursery to Grade 4 with its desire to give the essential foundation of education and character of young Malvareños.
At present, Southgate officially functions as a provider of quality education from Nursery to Grade 6, Junior and Senior High School, gearing young Malvareños to face future challenges.