Williams is the elder of two children. His father Gary Williams has been heavily involved in the development of baseball in Australia. Both Gary and Glenn Williams have represented their native Australia in international baseball competitions.
In 1993, as a 16-year-old, Glenn signed a lucrative free agent contract with the Atlanta Braves for an estimated 1.3 million Australian dollars. He played baseball for the minor league affiliates of the Atlanta Braves, Toronto Blue Jays, and Minnesota Twins.
After spending over 10 years in the minor leagues, Glenn made his major league debut with the Minnesota Twins during the 2005 season. In 2007, Glenn played for the Minnesota Twins Triple-A affiliate team, the Rochester Red Wings. Williams had a 13-game career hitting streak, as he had a hit in every game that he played in while in the major leagues.
