A student from Warragamba Public School has tested positive for coronavirus.
Health authorities say the school will be non-operational for the on-site attendance of staff and students while the school conducts contact tracing and is cleaned.
Staff and students who are identified as a close contact will be contacted and advised they should self-isolate for the required period of time.
The Berejiklian government had hoped students would begin a gradual transition back to the classroom next week.
State and Federal Government have repeatedly quoted health advice which said schools remain a safe place from the virus.
A statement from the school on its NSW Department of Education website said the safety and wellbeing of its staff and students were of paramount importance to the school at all times.
"As such we will continue to work closely with NSW Health to ensure that all necessary health advice is adhered to," the statement said.
"The school will continue to support students with the existing at-home learning arrangement while the school site is non-operational. Learning materials are available online through the Department's learning from home site."