The Hills Grammar School (commonly referred to as Hills Grammar) is an independent nonsectarian co-educational early learning, primary and secondary day school, located in Kenthurst, a suburb in the Hills district of Sydney, New South Wales, Australia.

Established in 1982, the school has a non-selective enrolment policy and currently caters for over 1,000 students from early learning, through Kindergarten to Year 12. In 2010, the school opened the Early Childhood Education Centre (ECEC), catering for 3–4 year olds. Main intake years are ECEC, Kindergarten, Year 7, and Year 11; however, if vacancies exist in other years, admissions can be made.

Hills Grammar is affiliated with the Association of Heads of Independent Schools of Australia (AHISA), the Heads of Independent Co-Educational Schools (HICES) and the Junior School Heads Association of Australia (JSHAA).