The Royal Newfoundland Constabulary said the suspect, 56, took the ambulance around 7:30 p.m. after paramedics arrived in Meadowbrook Park in the Goulds area of the city.
The Eastern Health ambulance was recovered a short time later, and was not damaged.
The suspect faces charges of impaired driving and joyriding, and was taken to the city lockup. He is expected to appear in provincial court in St. John's on Thursday.
Police said the incident did not delay the paramedics or affect any patients.
An RNC official said "the bright lights of an ambulance might be nice and flashy, but the siren gets old real quick."
Eastern Health, meanwhile, is looking into the incident, to ensure that staff followed appropriate protocols while responding to the call.
"Eastern Health is very concerned that its ambulance was taken while responding to an emergency call," the authority said in a statement Thursday.
"While this incident did not cause a delay in providing care to the patient, the ramifications of such an act could have, and as such, Eastern Health takes this incident very seriously."
The authority added that its ambulances are equipped with what it described as anti-theft systems.Suggest a correction