Joshua Dale Brown, 26, was charged on May 12 with more than 70 offences connected to eight victims at a childcare centre at Point Cook in Melbourne's west between April 2022 and January 2023.
Sexual penetration of a child under 12, attempted sexual penetration of a child under 12, sexual assault of a child under 16 and producing child abuse material are amongst the serious charges.
The children were aged between five months and two years at the time of the alleged offending, Victoria Police say.
Brown was not known to police, and there were no formal complaints against him before his arrest.
The Point Cook man had a valid working with children check, which has since been cancelled.
The families of his alleged victims were notified last week.
"This was deeply distressing for the families to hear," Victoria Police Acting Commander Janet Stevenson told reporters on Tuesday.
His arrest has led to a broader investigation by the sexual crimes squad, which has established he worked at 20 childcare centres between January 2017 and May 2025.
The centres are mostly in the city's west including Point Cook, Wyndham Vale, Williamstown, Sanctuary Lakes, Werribee, Leopold, Footscray, Sunbury, Hoppers Crossing, Melton, Kensington, Keilor, Essendon and Bundoora.
An allegation of offending at a second childcare centre in Essendon has been made and is under police investigation.
An estimated 2600 families and carers who had children placed at the centres during his employment are being sent letters with important instructions.
Police are not currently alleging the man offended at the other centres and urge anyone with information to contact Crime Stoppers.
Health authorities warn that many children may have had a low risk of exposure to infectious diseases.
"At this stage, we are recommending that around 1200 children undergo testing for infectious diseases," Victorian chief health officer Christian McGrath said.
Officials would not disclose the types of infectious diseases, but said they were treatable with antibiotics.
Police believe all of the alleged offending happened within Victoria and there is no evidence to suggest any other staff were involved.
Authorities do not usually comment on matters before the courts but broke protocol after a suppression order was lifted.
Premier Jacinta Allan said parents and childcare educators would feel "sick to the stomach" at the allegations.
"The allegations against this one individual by no means is a reflection of the work that is done across the sector," she said.
Brown remains on remand and is expected to face court on September 15.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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