Ryan Cho, 29, entered the pleas in Melbourne Magistrates Court on Thursday morning, a year after he was first charged.
He admitted concealing a phone in a mesh bag inside staff toilets at the Austin Hospital, the Peter MacCallum Cancer Centre and the Royal Melbourne Hospital.
Police say the material found on the phone showed staff using the toilet or shower facilities, with their genital and anal areas exposed.
The files were created in 2024 and 2025, and were categorised into different folders referencing each of the three hospitals.
There were also thousands of images found of a single victim that Cho admitted to stalking between October 2020 and September 2021.
Cho was initially charged and remanded in custody in July 2025 on five charges but he successfully applied for bail in the Supreme Court in August.
In the ensuing months, police laid hundreds of additional charges, with the total reaching 910.
But after a plea deal with prosecutors, Cho on Thursday pleaded guilty to 13 rolled-up offences including producing an intimate image, installing a device and stalking.
Magistrate Michelle Mykytowycz found the evidence was sufficient to support a conviction and she ordered the case be uplifted to the Victorian County Court.
Cho only spoke during the brief hearing to confirm his guilt and that he understood his continuing bail conditions.
They included not being allowed to attend a hospital unless there is an emergency.
He will face the County Court in November for a plea hearing.
Cho has repeatedly tried to avoid reporters waiting outside by remaining in the court building for hours after his case concluded.
He has also covered his face behind masks, sunglasses and a cap to avoid cameras.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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