An Ofsted report said Chris Oakley, head of Luton Pentecostal Church Christian Academy, had not checked whether the animals posed a risk to his pupils before bringing them into the school.
The Ofsted report said: "The proprietor has not ensured that all necessary risk assessments are carried out and that they are updated regularly.
"A seven-foot-long boa constrictor and a number of tarantulas are kept in the principal's office. No risk assessment has been made to ensure that keeping such animals in school does not pose a risk to children."
The school charges students tuition fees of £3,300 a year. The Ofsted report deemed its teaching "inadequate".
Chris McGovern, chairman of the Campaign for Real Education told the Telegraph: "Schools should stick to mice, tadpoles and goldfish."
Premier has contacted the school for comment.