Mark Petkovsek's journey through Major League Baseball began when he was drafted by the Texas Rangers in the first round of the 1987 amateur draft. A right-handed pitcher, Petkovsek made his MLB debut with the Rangers on July 29, 1991. His time with the Rangers was brief, as he appeared in only a handful of games before moving on to other opportunities.

After his stint with the Rangers, Petkovsek spent some time in the minor leagues, honing his skills and working to return to the majors. His perseverance paid off when he joined the Pittsburgh Pirates in 1993. However, his tenure with the Pirates was also short-lived, as he pitched in only a few games for the team.

Petkovsek's career took a more stable turn when he signed with the St. Louis Cardinals. It was with the Cardinals that he found a more consistent role, pitching for the team from 1995 to 1998. During his time in St. Louis, Petkovsek was utilized both as a starter and a reliever, showcasing his ability to adapt to the needs of his team. His most productive season came in 1996 when he recorded a 11-2 win-loss record, primarily as a starter, and helped the Cardinals reach the postseason.

Following his years with the Cardinals, Petkovsek joined the Anaheim Angels in 1999. He continued to serve as a reliable option out of the bullpen and occasionally as a starter. His experience and steady presence on the mound were valuable assets to the Angels during his time with the team.

In the latter part of his career, Petkovsek returned to the Texas Rangers in 2001, the team with which he had begun his major league journey. He pitched in a limited capacity before retiring from professional baseball.