St Brendan's enrolment policy follows the Sydney Archdiocesan Catholic Schools Enrolment Policy which is available on the Sydney Catholic Schools website. Priority of enrolment is given to the families as listed in this policy.

Kindergarten enrolment applications are taken in March of the year prior to starting school. Kindergarten children must turn 5 years of age by 31 July of the year they commence school. Enrolment takes place within the timeframe outlined by the Sydney Catholic Schools. An Enrolment Committee considers all applications. All other enrolments are considered throughout the year depending on vacancies.