After playing three seasons in the OHL and representing the U.S. in the 1987 World Junior Championships, Mike Hartman was selected by the Buffalo Sabres in the 1986 Entry Draft. Given that he was Buffalo's eight pick, and 131st overall, it came as a surprise to some people that he made the team on his first try. The coaching staff, impressed with his toughness, played him 17 times in his first NHL season. The next year, he appeared in 18 games with the Sabres and spent the balance of the season honing his game with the AHL Rochester Americans. It was back to Buffalo full-time, however, for the next three seasons.
He continued to play tough hockey, though, posting more than 100 penalty minutes annually. He had an NHL career-high 21 points in 1989-90. Hartman was traded to Winnipeg in a multi-player deal in October 1991. He played a year for the Jets before being claimed by Tampa Bay in the 1992 Expansion Draft. After 58 games with the Lightning, Hartman was traded to New York and spent part of the next two seasons with the Rangers before returning to the minors. He moved around various leagues in the U.S. before heading to Europe, where he played a year in Germany. Hartman retired from professional hockey in 1999.