Denny Stark, a right-handed pitcher, embarked on his Major League Baseball (MLB) journey when he was drafted by the Seattle Mariners in the third round of the 1996 MLB Draft. His professional debut came in 1999 with the Mariners, where he began to hone his skills on the mound. Stark's time with Seattle was brief, as he appeared in only a handful of games over two seasons.

In December 2001, Stark's career took a new direction when he was traded to the Colorado Rockies as part of a multi-player deal. It was with the Rockies that he found more opportunities to showcase his abilities. The 2002 season marked a turning point for Stark, as he became a regular part of the Rockies' pitching rotation. That year, he achieved a 3.81 ERA over 32 games, including 20 starts, and recorded 11 wins. His performance was a bright spot for the Rockies, who were navigating the challenges of playing in the hitter-friendly Coors Field.

Stark's tenure with the Rockies continued through the 2004 season, although he faced challenges with injuries and consistency. In 2003, he struggled with a higher ERA and fewer wins, and injuries limited his appearances in 2004. Despite these setbacks, Stark remained a part of the Rockies' pitching staff, contributing both as a starter and a reliever.

After his stint with the Rockies, Stark spent time in the minor leagues, working to regain his form and return to the majors. He signed minor league contracts with several teams, including the Cleveland Indians and the Chicago White Sox, but did not make a significant return to the MLB during these years. His perseverance in the minors demonstrated his continued pursuit of a place in the major leagues.

Stark's career in professional baseball concluded after the 2009 season.