Ryan Yi Cho, 29, entered the pleas in Melbourne Magistrates Court on Thursday, with his case now uplifted to the Victorian County Court.
A three-day plea hearing has been set aside for November where his victims will be given the chance to read statements to the court, detailing the affects of his crimes.
Cho 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 hundreds of staff members using the toilet or shower facilities, with their genital and anal areas exposed.
Thousands of files were created in 2024 and 2025, and were categorised into different folders referencing each of the three hospitals.
Detectives also located more than 3000 images of a woman Cho stalked 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.
Cho will face the County Court on November 23 for his plea hearing.
His registration as a medical practitioner remains suspended and he cannot practise anywhere in Australia.
Cho waited inside the court building for more than four hours on Thursday to avoid reporters and cameras waiting outside.
He has repeatedly covered his face behind masks, sunglasses and caps at each of his court hearings.
A Royal Melbourne Hospital spokeswoman told AAP they could not comment on the case but the hospital's focus remained on supporting its people and their wellbeing.
Peter Mac was also providing support to its staff, a spokesman said.
"This has been a distressing period and one that has had a lasting impact on many staff at Peter Mac," the statement to AAP read.
Austin Health declined to comment.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
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