Prior to entering politics, Heng had worked at the Singapore Police Force (SPF) and National Trades Union Congress (NTUC).

He made his political debut in the 1997 general election as a solo PAP candidate contesting in Hougang SMC against the Workers' Party's Low Thia Khiang.

Born in a Chinese Singaporean of Teochew descent family, Heng was educated at Raffles Institution before graduating from Fitzwilliam College, Cambridge at the University of Cambridge in 1983 with a Bachelor of Arts with second upper class honours (later replaced by an Oxbridge Master of Arts) degree in economics under an undergraduate scholarship conferred by the Singapore Police Force (SPF) in 1980.

He subsequently went on to complete a Master of Public Administration degree at Harvard University's John F. Kennedy School of Government in 1992 under a postgraduate scholarship conferred by the Singapore Police Force (SPF).

The PAP team won with 74.48% of the vote against the Singapore Democratic Alliance[5] and Heng was elected as the Member of Parliament representing the Whampoa ward of Jalan Besar GRC.

In the 2006 general election, Heng contested in Jalan Besar GRC again as part of a five-member PAP team and they won with 69.26% of the vote against the Singapore Democratic Alliance.

During the 2011 general election, Heng contested as a solo PAP candidate in the newly formed Whampoa SMC and won with 66.1% of the vote against the National Solidarity Party's Ken Sun.