Eynesbury Senior College is an independent co-educational senior high school on Franklin Street in the city center of Adelaide, the capital of South Australia. The college comprises a modern, five-storeyed, multi-function complex and caters for Year 10, 11 and 12 students. Its adult learning environment and its different approach to senior secondary education characterize the college. Noticeably absent are extra-curricular activities, extensive sporting programs, festivals and other activities, which are a feature of traditional schools. As a result, teachers are available outside scheduled class times for extensive one-to-one support. Students are encouraged to see their teachers as colleagues and are free to address them by their first name.

Eynesbury is known for its record of consistent academic success. The median Australian Tertiary Admission Rank of its students has been around 87-90 each year with about 95% going on to undertake tertiary studies Eynesbury became a registered school on 1 October 1989. The first intake of Year 11 and Year 12 students was in mid-January 1990, with an initial enrolment of 140 students. The school was initially registered as Eynesbury House Senior Secondary College. However, it became known as Eynesbury College.

By 1995, the school had outgrown the Kingswood Campus and, in January 1996, a second larger campus was opened in Franklin Street in the heart of the city of Adelaide. Eynesbury remained a two-campus school until the end of 2001, when teaching was consolidated at an expanded and upgraded Franklin Street campus. Redevelopment of the Franklin Street campus took place over several stages. The first stage involved an extensive upgrade of electrical services, fire protection and the construction of laboratories.

 This was followed with the rebuilding of reception areas, the construction of additional computing classrooms and science laboratories, and the redevelopment of the outdoor terrace on the second floor as a modern, cafe-style recreation area for students. A new Drama center was opened in July 2005. In Eynesbury's largest single capital development, the building's air conditioning plant was replaced in 2006. The original two lifts of the Franklin Street campus were replaced in early 2009.Eynesbury celebrated its 20th birthday in 2009 with the opening of a new campus. Located in Coglin Street, Adelaide, the new campus is the location for the majority of Eynesbury's international students. The Eynesbury Institute of Business and Technology (EIBT) moved to the new campus in April 2009 and other programs followed soon after.