Tseung Kwan O Government Secondary School - a grammar school - was set up as part of the School Renewal Programme of the Education Bureau (formerly the Education Department). The precursor of TKOGSS was Kennedy Town Government Secondary School). At the beginning, the site of the school was Lot No.22, Tseung Kwan O, which was later re-named No.2 King Yin Lane. The commencement of classes in September 1988 was followed by an Opening Ceremony on 1st March 1990 which was presided over by Mrs. Allan Lee (Mr. Allan Lee being the first Legislative Councillor). Mr. Lee Yuet-ting, Director of Education, delivered the opening speech. Since then, TKOGSS has become one of the oldest secondary schools in the Tseung Kwan O New Town. The maxim "Prepare yourself that you may serve" was adopted in 1998 as the school motto, which serves to inculcate in the students a moral character and a will to strengthen themselves constantly, as well as respect for others and a spirit of co-operation in group life. In this way, they will be able to serve the community and fulfil what is given in the lyrics of the school songs --- live a decorous and self-disciplined life; look after and provide for one's family; ensure good governance of the state and bring peace and stability to the world; explore the nature of things and hence apply one's intellect, successfully serve one's motherland in return.
With the development of new concepts and ideals in education, the school has been actively encouraging students to learn with the help of information technology. Starting from 1998, each classroom has been equipped with a television set, a projector, a loudspeaker, a recorder and a computer screen. The year 2000 witnessed the opening of the Multimedia Learning Centre. A campus TV network was installed in 2001. In 2003, a video camera and a built-in computer desk for the use of teachers were installed in each classroom, where audio-visual equipment was also updated, to facilitate multimedia teaching by teachers.
As the existing premises were found to be inadequate for the development of the school, the School Improvement Project was started in 2002. In April 2003, a new wing was officially completed and ready for use, the area of the school site increasing from 7,000 to 8,500 square metres. The space for class teaching and activities was thus greatly increased. The new wing of the school building was opened by Mr. Cheng Yan-tse, deputy permanent secretary of the Education Bureau on 22 April, 2004.
The completion of the new wing has increased the space and facilities for activities: the mini-hall for table tennis; the Student Activity Centre has become the favourite of the Dancing Group. Other places like the library, the language room, the conference room, the geography room, the music room, etc, open up new possibilities for teachers and students alike.