The Good Schools Guide described the school as "a super no-frills choice: big enough to appeal to almost any girl, but not at the expense of the personal touch".
Portsmouth High School was founded by the Girls' Public Day School Trust (now the Girls' Day School Trust) in 1882. The school moved to its present premises on Kent Road in Southsea in 1885, when the building was opened by Princess Louise. Dovercourt, the house built and lived in by the Southsea architect Thomas Ellis Owen, was acquired for the Junior School in 1927. During World War II the school was evacuated to two country houses in Hampshire, Hinton Ampner (Junior Pupils) and Adhurst St Mary (Senior Pupils), and became a boarding school for six years. After the war, the school became a direct grant grammar school under the Education Act 1944 and became independent during the mid-1970s when the scheme was abolished.
Portsmouth High has an excellent academic track record in examinations. In 2016 percentage number of A levels graded A or A* was 43% and the number of A Levels graded A* to B was 80%. In GCSEs 68% of all grades were A*/A, 91% were A* – B and 100% were A* – C.