Sim Ker Song started his career in 1998 as a Planning Engineer with Foster Wheeler Eastern (Pte) Ltd in Singapore. His first assignment brought him to the then Esso Refinery in Pulau Ayer Chawan where he first experienced the dynamic environment of brownfield site revamp construction. He worked as a Planner in The Singapore Chemical Complex (SCC) - Refinery Interface Facilities Project which involved new facilities that interface with SCC, the largest petrochemical plant in Singapore being constructed on the newly reclaimed Jurong Island.

After almost 5 years with Foster Wheeler, Ker Song joined Yokogawa Engineering Asia Pte Ltd as a Project Controller for the Main Automation Contractor delivering automation systems to the multi-billion value CSPC Nanhai Petrochemicals Complex Project in Huizhou, China. During his 8 years with Yokogawa, he helped set up and develop the Project Controls function and systems which was subsequently used in major Main Automation projects like Saudi Aramco PetroRabigh Petrochemicals Project and INPEX.

In 2010, Ker Song left Yokogawa to join Chiyoda Singapore (Pte) Ltd as the Project Controls Manager in charge of SCOT BUGIS Projects in Shell Bukom.