[1][2][3] Previously, he served as the Minister of Local Government Sarawak from May 2016 to January 2017 under Adenan Satem's cabinet, and Minister of Local Government and Housing Sarawak from January 2017 to December 2021 under Abang Johari's first cabinet.

Nonetheless, his father's personal values and passion in public service had rubbed-off on his character, and a chance to serve his homeland came when Sim found out that the Sarawak General Hospital (SGH) was attempting to set up a cardiology unit.

In 1974, then Prime Minister of Malaysia Abdul Razak and Sim's father, Sim Kheng Hong (who was with Deputy Chief of Mission Tun Jugah representing Sarawak in the delegation), were among the people who helped establish the foundations of Malaysia-China bilateral relationship.

Sim currently still holds a medical practising license and specialist license, and still makes frequent visits to the Sarawak General Hospital (SGH)'s Sarawak Heart Centre as a visiting senior consultant cardiologist.

Having spent over 10 years as the inaugural head at the SGH Department of Cardiology (the third public cardiac centre by the Ministry of Health Malaysia) and subsequently as the inaugural head of its Clinical Research Centre (CRC), Sim is today the advisor at SGH CRC and advisor at the National Heart Association of Malaysia.

[27] Other professional positions he holds include: the immediate past president, Asian Pacific Society of Cardiology (APSC); international governor steering committee (Asia Pacific region) of the American College of Cardiology; board member of World Heart Federation; executive committee member of the Asian Society of Cardiac Imaging (ASCI); council member and past president of the National Heart Association of Malaysia (NHAM); and the past secretary general of the Asian Pacific Society of Interventional Cardiology (APSIC).