Coffey was drafted 6th overall by the Edmonton Oilers in the 1980 NHL Entry Draft. He blossomed in the 1981–82 season, scoring 89 points and was named a Second-Team NHL All-Star. In the Oilers’ first Stanley Cup-winning season, 1983–84, he became only the second defenceman in NHL history to score 40 goals in a season. He won his first James Norris Trophy in 1984–85 while posting 121 points. On December 26, 1984 in a game against the Calgary Flames, Coffey became the last defenceman in the 20th century to score four goals in one game.