Williamson was a first-round draft pick (fourth overall) by the Milwaukee Brewers in the 1994 Amateur Draft. He played minor league baseball for most of his career, and had a .271 batting average, and 415 hits in his six-year minor-league career. Williamson's only major league action came in a 24-game stint in 1997 for the Brewers. In those 24 games, he recorded a .204 average. He played first base, and occasionally pinch-hit.