Ar. Zainal started his career by joining Kuala Lumpur City Hall (DBKL) in 1981 as an assistant to Architect. He then furthers his studies in Architecture in the University of Newcastle, Australia and returned to join DBKL as Architect in 1984. His responsibilities included designing and managing residential developments, public buildings including mosque and suraus, community halls and a resort development for DBKL in Port Dickson, Negeri Sembilan. His involvement in prefabricated housing development throughout Kuala Lumpur for DBKL has been recognized by the United Nation as an example of a successful relocation of squatters and low incomers programme by a local authority
He then furthers his studies at the Institute for Urban Development and Housing Studies, Rotterdam, Netherlands, majoring in Environmental Planning. He then joined Kuala Lumpur City Centre Berhad in 1992 as a manager responsible for the master planning of the Kuala Lumpur City Centre Development.
His responsibilities included matters with regards to land and development, the North-West Development where the World’s tallest building- the 88-storey PETRONAS Twin Towers sits, the KLCC Park and infra-structural services; and development proposals for the KLCC Transportation and Traffic System, Redevelopment of Victoria Station-Bombay, India., proposed High End Apartment and proposed new DBKL Headquarters, Jalan Ampang, Kuala Lumpur . He was promoted as the Principle Architect in the KLCC Architects Division and his responsibilities includes being the Architect for the KLCC projects including the 88-storey PETRONAS Twin Towers, the District Cooling Centres, KLCC Mosque and the KLCC Park. In 1995, Zainal ARCHITECT was founded and Ar. Zainal continue to provide his professional services to Kuala Lumpur City Centre Berhad as the Architect for the KLCC projects.