Greg J. Chalmers (born 11 October 1973) is an Australian professional golfer.
Chalmers was born in Sydney. He won the 1993 Australian Amateur and the 1994 French Amateur.
Chalmers turned professional in 1995 and made a strong start to his professional career, winning four times in Australia in the next few years, including the 1998 Australian Open. In Europe he won the second-tier Challenge Tour's Challenge Tour Championship, in 1997 and finished twenty fifth on the European Tour Order of Merit in 1998. The same year he finished fourth at the PGA Tour's Qualifying school to win a PGA Tour card for 1999.