As a young man, Boonchu tried for a career in kick boxing, but he gave it up after being knocked out cold in his third bout. He made his mark in golf when he won the 1985 Australian Amateur and he turned professional the following year. He has won five titles on the Asian Tour since its first modern season in 1995, and has several other victories to his name. He was the runner-up on the Asian Tour Order of Merit in 1995 and also made the top ten in 1998 and 2004. In the latter year he won the Thailand Open for the second time in his career at the age of 47.
In 2006, Boonchu turned 50 and became eligible to play in senior tournaments. He finished first in the 2006 Champions TourQualifying School and joined the Champions Tour in 2007. In 2010, he joined the European Seniors Tour and won four events (including three straight) and the Order of Merit.