The Corrections Department says all people applying for jobs within the organisation will face drug-testing from later this month.
A number of changes are being made to its recruitment process - including more credit checks and asking all applicants to declare any conflicts of interest.
All applicants will now also face enhanced police vetting - as opposed to a basic criminal check.
Organisational development general manager Vince Arbuckle says current staff members wanted new applicants to be screened for drug use.
He says the move makes it clear to people thinking about applying for a job that they have to be clean, as they will be working very closely with offenders - some whom have drug problems.
Mr Arbuckle says the department has no plans to introduce spot drug-testing for current staff.
The Drug Foundation says drug-testing all people applying to work at Corrections will not solve the wider problem of drugs in prisons.
The body says a growing number of employers place too much faith on drug tests.
Its executive director, Ross Bell, says Corrections would be better served addressing its workplace culture.
He says the prison environment is one of the worst to work in - and prisoners can manipulate or blackmail staff into bringing in drugs.
Mr Bell says a simple test is not going to address those very complicated matters.