Ian Greig MacCulloch was approaching 10 years' service at Kambala girls' school when he began to systematically defraud it.
MacCulloch, then the business manager of the Rose Bay Anglican school, went on to steal more than $364,000 between 2008 and 2013.
He received six Westpac credit cards on the school's behalf but spent the money on himself. On one credit card he racked up more than $100,000 of purchases.
Caught in late 2013, MacCulloch pleaded guilty to four counts of obtaining money by deception and four counts of dishonestly obtaining property.
Waverly Local Court Magistrate Clare Farnan sentenced MacCulloch on Tuesday to two, overlapping jail terms of nine and 18 months. But Magistrate Farnan allowed the offender to avoid time behind bars by serving an Intensive Corrections Order in the community instead.
A police fact sheet tendered in court said the the 56-year-old Normanhurst man had had little contact with police before he embarked on his "systematic and long-term defrauding".
Police said he had co-operated with their investigation and had shown remorse. It is understood he paid back a substantial amount of money to the school.
"There is no doubt that the fact that a trusted employee had perpetrated fraud is extremely disappointing to us all," Kambala Principal Debra Kelliher said in a statement on Tuesday.
Ms Kelliher said the school had made changes to reduce the risk of fraud after an extensive review of its financial protocols.
