Mearns Castle High School is a secondary school situated on Waterfoot Road in Newton Mearns, East Renfrewshire, Scotland roughly seven miles (eleven kilometres) from Glasgow.

It was built in 1978, and pupils from Eaglesham Primary, Kirkhill Primary, Maidenhill Primary, Calderwood Lodge and Mearns Primary are all part of the school's catchment area.

Mearns Castle is situated next to Maxwell Mearns Church which hosts some Christian services for pupils.

It is also positioned next to Mearns Castle (15th century), hence the name, "Mearns Castle High School".

The school's Senior Concert Band achieved significant success in the NCBF competitions achieving Gold Awards at both a Regional and National Level.