Walker played in Major League Baseball with the Cleveland Indians (1988, 1990, 1991), Chicago Cubs (1995), and Detroit Tigers (1996).

[6] He pitched 2.1 scoreless innings in relief of Rich Yett at Fenway Park against the Boston Red Sox.

[7] He made two more appearances in the Major Leagues that year and spent the entirety of the following season in Triple-A Colorado Springs despite remaining on the 40-man roster.

Walker, who by that point was pessimistic about his career prospects, was added to the big league roster in June.

[15] Walker had improved his control by studying his pitching mechanics on video during the offseason and cut his walks in half.

[17] To his surprise, Walker was demoted to the minor leagues in late July despite leading the bullpen in earned run average and innings pitched.

[18][16] During the 1995–96 offseason, Walker worked out with Mike Marshall, a former Cy Young Award winner who also had a doctorate in kinesiology.

[21] He appeared in twenty games in relief for the Tigers that season and was demoted to the minors for the final time on July 13, 1996.

[17] Prior to the 1999 season, the Cleveland Indians signed Walker to a free agent contract and invited him to spring training.

[2] In July 1999, he was playing in Cleveland's farm system for the Buffalo Bisons when he was released and opted to retire from professional baseball.