Rob DiMaio was selected 118th overall in the 1987 NHL Entry Draft by the New York Islanders from the Medicine hat Tigers of the WHL. DiMaio had a four-year junior career, which began at age 16 with the Kamloops Blazers in 1984. In his draft year, DiMaio averaged exactly a point a game, scoring 27 goals and 43 assists for 70 points in 70 games. His 130 minutes in penalties showed he was willing to mix it up with the bigger players if need be, and being a major contributor in winning the Memorial Cup didn't hurt his big-league aspirations, either. As a 19-year-old in his final year of junior, DiMaio put together a season of 47 goals and 44 assists for 91 points and, along with 17-year-old Trevor Linden, was a big reason why the Tigers were able to repeat as Memorial Cup champs, where he was named MVP of the tournament. In his second year of pro hockey, DiMaio was a member of the 1990 Calder Cup winning Springfield Indians in the AHL. DiMaio made his NHL debut on January 8, 1989 and scored his first goal five nights later on January 13 against the New Jersey Devils. In 1991-92, he joined the NHL ranks full-time and scored seven points in 50 games.



On June 18, 1992, the Tampa Bay Lightning claimed DiMaio in the Expansion Draft. In his first season with his new team, he scored 24 points. In 1993-94, he was traded to the Philadelphia Flyers. Then, in the shortened 1994-95 season, he helped the Flyers win the Atlantic Division title and reach the playoffs for the first time in six years. In the playoffs, DiMaio scored six points in 15 games as the team advanced to the Eastern Conference finals before losing to the Devils. In 1995-96, he scored 21 points with the Flyers as they repeated as Atlantic Division title winners. On September 30, 1996, the San Jose Sharks claimed the feisty forward in the Waiver Draft. That same day, he was traded to the Boston Bruins for a fifth round draft pick. In his first season with the Bruins, DiMaio scored 28 points including three short-handed goals. In 1997-98, he was a key contributor to the Bruins improving 30 points under Coach-of-the-Year Pat Burns. In 1999-00, DiMaio was sent to the New York Rangers for Mike Knuble. In keeping with the trading theme, August 4, 2000, saw him traded with Darren Langdon to the Carolina Hurricanes. In 74 games that year with the Hurricanes, he scored 24 points. In the summer of 2001, DiMaio signed as a free agent with the Dallas Stars and has continued to play a grinding and gritty game in the Lone Star State. During the 2003-04 season, he surpassed the 800-game plateau before returning to Tampa Bay in the summer of 2005.