Mamat was born in Singapore. He turned professional in 1994.
Mamat plays on the Asian Tour, where he won for the first time at the 2004 Royal Challenge Indian Open. In 2006 he won the Singapore Masters, which was co-sanctioned by the Asian Tour and the European Tour. This made him the first player from Singapore to win a European Tour event, and earned him a two-year exemption into the European Tour.
Mamat was the first Singaporean to play in the British Open when he qualified in 1997. He has also won several minor professional tournaments and was a member of the winning Rest of Asia team at the 2004 Dynasty Cup.