Ley was drafted by the Toronto Maple Leafs in the third round in the 1966 NHL Amateur Draft. He played four seasons with the Maple Leafs in the NHL before leaving to play with the New England Whalers of the WHA. He would remain with the Whalers' organisation in the WHA until that league folded in 1979. The Whalers, along with three other teams from the WHA's remaining six, were absorbed into the NHL in 1979. Ley made the transition with the New England Whalers and finished his professional playing career in 1981. Ley spent six years as the Whalers' captain and was one of three players in Hartford Whalers' history to have his jersey number retired, joining Gordie Howe and John McKenzie. Following the Whalers move to Raleigh, the Hurricanes ceased to honor Ley's #2 and McKenzie's #19, and returned the numbers to circulation, although #2 was re-retired by the Hurricanes, this time in honor of Glen Wesley. Ley and his wife Ellen have a daughter, Kathleen.
Ley began his coaching career in International Hockey League, where he coached the Muskegon Lumberjacks to four first-place finishes and one championship during his tenure between 1984 and 1988. He was then hired by former Leafs defence partner Pat Quinn to coach the Vancouver Canucks IHL affiliate in Milwaukee. After one season there, Ley was the coach of the Hartford Whalers for 2 seasons from 1989 to 1991, leading them to consecutive 4th-place finishes and first round playoff defeats at the hands of their New England rival the Boston Bruins in both seasons. Ley then rejoined the Canucks. After serving as an assistant coach under Quinn for three seasons from 1991–92 to 1993–94, Ley became the 12thhead coach in Vancouver Canucks' history on August 10, 1994. In 121 regular season games as head coach, the Canucks posted a record of 47–48–26. He also served the Canucks in a professional scouting capacity in 1996–97 and 1997–98. In 1998, he was once again hired by Quinn as an assistant coach with the Toronto Maple Leafs and held that role for eight seasons until he was relieved of his duties at the conclusion of the 2005–06 season.
