Victorian public school students will begin receiving access to on-campus mental health professionals from mid-July.

The rollout of the state government's $51.2 million election promise to put 190 psychologists, social workers and mental health nurses into secondary schools starts in 33 schools Melbourne's southeast in term three.

"It will take some time to have these professionals recruited and the services offered right across the state," Premier Daniel Andrews told reporters on Wednesday.

"But I'm very confident this is exactly what's needed in an increasingly complex world, providing vulnerable Victorians and particularly teenagers the care and support they need."

Mr Andrews made the announcement at Elwood College, in Melbourne's inner south, which will receive support two-and-a-half days a week under the program.

From term four, the program will expand to 21 secondary schools in Victoria's southwest and eventually every state high school will receive between one and five days a week of support from a practitioner.

Mr Andrews said if the current royal commission into mental health recommends expanding support in schools, his government would do so.