The Christian theme park was sold to the hospital chain in August.
AdventHealth will turn the former site of The Holy Land Experience in Orlando into a medical facility over two phases of construction.
During the first phase, the hospital system will build a 78,000-square-foot, four-story standalone emergency room and medical office on the site.
Then the second phase will see a five-story, 261,500-square-foot hospital building go up.
AdventHealth bought the Christian theme park last August for some $32 million dollars.
The park had been closed for two years during the pandemic, opening only briefing for two free family days in April.
Before that, more than 120 workers, mostly actors and stagehands, had been furloughed during the Easter holiday, one of the holiest times in the Christian calendar.