The school was founded in 1956 as Tanjong Katong Technical School (TKT), enrolling only male students. At first it occupied a plot of swampy marsh next to the river Tanjong Katong. The address of 369 Tanjong Katong Road was among a belt of upper-middle suburban housing and old Joo Chiat and Katong shophouses nearby. Its early years were rocky as there was a common misconception about technical schools that only less-academically inclined boys attended. Nevertheless, the school was considered the top technical school then. In 1969 TKT began to take in female students.
The added competition of neighbouring secondary schools in the Katong area also meant that TKT had to fare better academically as most families had originally automatically sent their children to the nearest school. The option of having Pre-U classes helped and the school population soared to an all-time high of 5000 in 1979.
For some years the school was called Tanjong Katong Secondary Technical School. In 1993 the school was renamed Tanjong Katong Secondary School because TKT was losing its technical focus and was focusing on offering mainstream curriculum like Humanities and Science.
In 1996, the school took over the premises of the neighbouring Tanjong Katong Girls’ School and began operating single-session.
In 1998 the school moved to its new premises at 130 Haig Road. The following year, TK was one of the pioneering schools to be awarded the Sustained Achievement Award when the award was first introduced. The opening ceremony of the new campus was held in 2000. The school became one of the Top 20 Value-Added schools in 2001. In 2003, it was presented with the Sustained Achievement Award for Value-Added. In 2004, the school made headlines when its graduating cohort of students achieved a 98% distinction rate for Chemistry in the GCE ‘O’ Level examinations, the highest ever in Singapore.
In 2004 the school was accorded Autonomous status. Following the new status came the School Distinction Award; the school was one of the pioneer 12 schools to be given the award. Another addition that year was the presentation of Singapore Quality Class status in recognition of the efficient organisation of the school. The academic curriculum in the school was recognised when it received the Best Practice Award for Teaching and Learning. Other areas were recognised with the achievements of Sustained Achievement Awards for Physical Fitness, Uniformed Groups and Value-Added.
In 2006 the school celebrated its Golden Jubilee. Senior Minister Goh Chok Tong joined in the celebration as the Guest-of-Honour. The school was presented the Sustained Achievement Award for Aesthetics and Best Practice Award for Student All-Round Development. The school band, Tanjong Katong Band, won the Best Display Band of The Year award for 10 years running, a feat no other secondary school in Singapore has achieved.
TK was presented the School Excellence Award in 2007. This is the most prestigious and the highest status of awards given by MOE. The school made headlines again as it is the 8th secondary school to be presented the award, alongside many top schools in Singapore. In the year 2007, the inaugural “Model Class Award” was awarded to Class 4C.