The MQM activist was identified as Farooq Baig, who was travelling in his car when unidentified gunmen ambushed him near Singer Chowrangi at Korangi No. 5.
He was rushed to Liaquat National Hospital where he succumbed to injuries.
After the incident four more people were gunned down in different parts of the city.
City wore a deserted look. Petrol pumps in most parts of the metropolis remained shut so were all major markets.
Public and private transport was thin. Aerial firing in different parts of Karachi forced people to stay indoors.
Unidentified miscreants also set on fire some 20 busses and resorted to aerial firing in different parts of the city.