St Marys Senior High School is a government-funded co-educational dual modality partially academically selective and comprehensive post-compulsory secondary day school, located in St Marys, a suburb in western Sydney, New South Wales, Australia.

[2] In 2008, a St Marys Senior High School student was awarded first place in the Society and Culture HSC exam.

[3] In the 2008 HSC exams, St Marys Senior High School had 5 students achieve recognition on the Board of Studies All Rounders List.

[3] In 2022, news broke out about George Danakis, a 44 year old man from Blacktown who was caught on St Marys Senior High School's CCTV to be having sexual intercourse with sheep, cows and goats throughout multiple nights in the school's barn.

His charges include break and enter, possession of an unauthorised firearm and three counts of bestiality.