Paramedics were called to the Stobswell shopping area following concerns for a male.
The man was found “slumped” on a park bench on Albert Street near the Spar shortly after 9pm on Tuesday.
One motorist said two paramedics were on the scene and placed a blanket over the patient.
Concerned security guards from neighbouring businesses had gone to the man’s aid before the paramedics arrived.
A spokesman for the Scottish Ambulance Service said: “We received a call at 9.26pm on Tuesday to attend an incident on Albert Street.
“We dispatched one ambulance to the scene and transported one male patient to Ninewells Hospital.”
The motorist, who lives locally, added: “I was worried about what had happened to the guy.
“There were plenty of folk on the scene to help, along with the paramedics. I just hope the guy is OK.”