The 26-year-old man allegedly took explicit photos of the victims while working at six out-of-school care service providers in the northern suburbs of Sydney and the city centre between April 2021 and May 2024.
He came to the attention of Australian Federal Police investigators after they found the material on the dark web, tracing it back to him in June 2024.
Digital forensic investigators were able to crack into the man's devices after he was initially charged over refusing to provide his passwords.
Details of the investigation were revealed on Thursday after court-issued non-publication orders were revoked.
The man has been remanded in custody since October 2024.
AFP acting Assistant Commissioner Brett James said police were vigilant in catching offenders lurking on the dark web.
"These pedophiles seem to think they can work under the cover of the dark web," he told reporters.
"The AFP can see you ... if you think you're under the cover of darkness, you're not and we're coming after you."
Investigators examined 142,000 files totalling about 19 gigabytes to comb through the child-abuse material.
Some 1200 parents at the six centres where the alleged offences took place were contacted by federal investigators.
The Artarmon man is alleged to have offended at six locations but parents at 52 other locations, including some of Sydney's most elite schools, where he worked on a casual basis have been notified.
NSW Police said the man was employed as a probationary constable from December 2021 to September 2022.
After he failed to successfully complete his probation, he continued in a civilian capacity until his resignation in May 2023.
Police said they were unaware he was working in the childcare sector at the same time.
The assistant commissioner noted the community should be aware that offenders do not fit a specific profile.
"These sort of individuals cross all industries, cross all parts of the community and we don't discriminate," Mr James said.
"We don't discriminate, we just deal with criminality and then we put those people before the courts."
Federal police said the man did not pose a current threat to the community.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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