Glendower Prep was founded in 1895 by Miss Lloyd and Miss Cornwall at 103A Fulham Road and was originally called "Cornwall and Lloyd School".

The school remained at this site from 1920 until 1939 when the Second World War forced an evacuation to Cornwall.

Glendower moved into 87 Queen's Gate in 1947 where it has remained with some extension and expansion until the present day.

As of 2020[update] the headmistress is Ms Kingsmill Moore.

Ms Claire Boyd became the headmistress in September 2024 The name Glendower itself is an anglicised pronunciation of the Welsh prince's name Owain Glyndŵr.