Bob Dillabough broke in to the NHL back in 1961 when he took to the ice for five games with the Detroit Red Wings. The Wings retained his rights for the 1962-63 season but his entire year was spent in Pittsburgh, playing with the Hornets of the AHL. In fact he played three years in Pittsburgh, only getting in to the Detroit lineup on four occasions.
In 1965-66, he was off to the Boston Bruins where he played 53 games, scoring seven goals and 13 assists for 20 points. He followed that up with a 60-game season, but his points production dropped slightly to 18.
The Pittsburgh Penguins grabbed him in the 1967 Expansion Draft and he wore the blue and white Pens uniform for 47 games, scoring seven goals and 12 assists. After beginning the 1968-69 season in Pittsburgh, Dillabough was shipped off to the Oakland Seals, one of the other new teams in the league where he played in 48 and 52 games, respectively. That would be his final NHL destination, although he did remain in pro hockey for another four years, playing with the Rochester Americans and the Tidewater Wings of the AHL before playing a full 72-games with the Cleveland Crusaders of the brand new rival World Hockey Association. Dillabough had eight goals and eight assists that year playing on a team that had Gerry Cheevers tending goal.
Dillabough's final professional season was in 1973-74, when he played in 51 games for the Toledo Hornets of the IHL. He had 14 goals and 23 assists for 37 points.