Returning to the lineup healthy for 1987–88, Loob became the first Swedish player in NHL history to score 50 goals in one season. As of the end of 2019–20 NHL season, he is still the only Swede to accomplish the feat. He also set a Flames franchise record by scoring five hat tricks during the season. He finished sixth in league goal scoring, while his 106 points was ninth in that category. Loob was named to the First All-Star Team on right wing, and was the winner of the Viking Award as the top Swedish player in the NHL as voted by his fellow Swedes. Loob scored 27 goals in 1988–89, but added 58 assists for the Flames. He added 8 goals and 17 points in the playoffs to help the Flames win their first Stanley Cup in franchise history. In the Cup clinching game against the Montreal Canadiens, Loob started a quick passing play with Joe Nieuwendyk on a three-on-one rush that set up Lanny McDonald's final NHL goal and gave the Flames a lead they would not relinquish.