Justin Gimelstob was born on January 26th, 1977 in New Jersey, USA. He turned pro in 1996 and is yet to win on the ATP Tour. Gimelstob began playing tennis at the age of eight. He was the US under 18's boys champion. He attended Newark Academy before turning pro.

The American is primarily a doubles specialist having won over a dozen titles. In 1998 he won the Australian and French Open mixed doubles with Venus Williams. In 2006 he reached the 2nd round at Wimbledon and the US Open and also had several Quarter Final appearances.