Nill played in the NHL throughout the 1980s with the St. Louis Blues, Vancouver Canucks, Boston Bruins, Winnipeg Jets, and Detroit Red Wings, retiring in 1990.

He did not stay in New Brunswick long as Detroit Red Wings head coach Jacques Demers liked his tough style of play and acquired him on January 11, 1988 in exchange for fellow journeyman NHLer Mark Kumpel.

Nill played the final three years of his NHL career in Detroit with brief stints for the AHL's Adirondack Red Wings.

Nill's duties with Detroit included directing their amateur scouting and selections at the annual NHL Entry Draft.

Nill continued to oversee the development of the Red Wings' prospects that are currently assigned to Detroit's main affiliate, the Grand Rapids Griffins of the AHL, as well as those in the Canadian junior and European leagues.

[1] On July 4, 2013, in a blockbuster trade, Nill sent 2011 NHL All-Star Loui Eriksson (as well as prospects Joe Morrow, Reilly Smith and Matt Fraser) to the Boston Bruins in exchange for former second overall pick Tyler Seguin as well as Rich Peverley and Ryan Button.

[2] On the same day, he traded prospect Philip Larsen and a seventh-round pick in the 2016 NHL Entry Draft to the Edmonton Oilers in exchange for their captain Shawn Horcoff.