Established in 1984,[2] approximately 4,000 students are enrolled over 5 different campuses in Evanston South, Angle Vale, and Blakeview, with a sixth planned to open in Roseworthy in 2024[3] Students from the College have been successful in the Rock Eisteddfod Challenge (3rd in the small school section in 2004), the Tournament of Minds (2003 Secondary Division in Maths Engineering) and the Wakakirri competition, with Gawler River earning a 1st place in the division one section for new schools and South receiving 1st in the division three section.

In 1994, the college purchased 2.16 square kilometres of bushland and created the Blackham Environmental and Conservation Centre.

Opened in 2000, the centre has four multi-purpose courts, one 25m and one small indoor heated swimming pools, gymnasium, café, theatre, and conference rooms.

The "Trinity Innovation and Creativity School" was opened in early 2020 and contains an art gallery, podcast studios, green rooms, 360 degree projection room, multiple classrooms, design studios and a sunken gallery with a large screen.

In 2021, an incident of alleged racism occurred involving two Trinity College Senior schoolgirls, who were reported to have lynched a black baby doll.