The city's first coronavirus case was confirmed by the Medical Superintendent (MS) of Fatima Jinnah Hospital on Tuesday.
A 12-year-old boy was said to have the virus. According to the MS, the boy had travelled to Taftan with his parents.
The parents were screened and were reported to test negative for the virus.
With the new case in Quetta emerging, the nationwide tally rose to 19.
Karachi has the highest number of cases, numbering 15.