The 1985 Stanley Cup playoffs, the championship of the National Hockey League (NHL) began on April 10, after the conclusion of the 1984–85 NHL season. The playoffs concluded on May 30 with the champion Edmonton Oilers defeating the Philadelphia Flyers 8–3 to win the Final series four games to one and win the Stanley Cup.
The following teams qualified for the playoffs:
- Montreal Canadiens, Adams Division champions – 94 points
- Quebec Nordiques – 91 points
- Buffalo Sabres – 90 points
- Boston Bruins – 82 points
- Philadelphia Flyers, Patrick Division champions, Prince of Wales Conference regular season champions – 113 points
- Washington Capitals – 101 points
- New York Islanders – 86 points
- New York Rangers – 62 points
- St. Louis Blues, Norris Division champions – 86 points
- Chicago Black Hawks – 83 points
- Detroit Red Wings – 66 points
- Minnesota North Stars – 62 points
- Edmonton Oilers, Smythe Division champions, Clarence Campbell Conference regular season champions – 109 points
- Winnipeg Jets – 96 points
- Calgary Flames – 94 points
- Los Angeles Kings – 82 points
In the series finale, the Canadiens got the only goal when Mats Naslund scored with just 51 seconds remaining in regulation. Steve Penney stopped all 20 shots to register the shutout.
In the final game, Buffalo led 5-3 with just nine minutes remaining, but allowed the Nordiques to score two goals in a span of 64 seconds to tie it at 12:06. The Nordiques' Brent Ashton then got the winner with only 69 seconds left.
The Quebec Nordiques and Montreal Canadiens battled in a seven-game series. Bitter rivals from the province of Quebec, the Nords shocked the Habs in 1982, only to see a fourth-place Montreal club upset Quebec two years later. In the deciding seventh game at the Montreal Forum, Peter Stastny scored the game and series winning goal, giving Quebec an improbable 3–2 overtime win and berth in the Wales Conference Finals. Quebec would not get to the conference finals again until 1996, their first year as Colorado Avalanche. They would win the Stanley Cup.
The Philadelphia Flyers ended the New York Islanders' string of five straight seasons in the Stanley Cup Final by dispatching the club four games to one. Flyers goaltender Pelle Lindbergh registered a pair of shutouts, one in the first game and the other in the clinching fifth game, by a 1–0 score.
The Chicago Black Hawks simply outscored the Minnesota North Stars in an offensive-minded six-game series that featured 61 total goals.
Defending Cup champion Edmonton was too much for the Winnipeg Jets, sweeping them in four straight games and doubling their goal total.
Although the Flyers held the best record in the NHL with 53 wins and 113 points, the Adams Division held a better record against the Patrick Division, so the Wales finals began in Quebec City. Philadelphia and Quebec split the first four games of the series, then the Flyers edged the Nordiques, 2–1 in game five. Game six in Philadelphia was a tour-de-force for the Flyers, outshooting Quebec 36–15, and winning 3–0. Flyers captain Dave Poulin's shorthanded goal early in the second period was the deciding factor in the contest. The team returned to the Stanley Cup Finals for the first time since 1980. The win came at a high cost for the Flyers as both 54-goal forward Tim Kerr and defenceman Brad McCrimmon would be lost for the remainder of the playoffs with injuries.
The Oilers defeated the Black Hawks in a six-game series which broke all sorts of records for total offense. Edmonton won the first two games at home by 11–2 and 7–3 scores, only to see Chicago strike back at home with 5–2 and 8–6 victories. However, Edmonton rebounded to blast the Hawks in the final two games, 10–5 and 8–2 to earn their third trip to the Cup Finals in as many years. Edmonton set all-time playoff marks with most goals in one series, most goals in a six-game series, and both clubs set records with most total goals in a semifinal series and most total goals in one six-game series. Oilers' Jari Kurri scored three hat tricks in the series, setting a still-standing NHL record.
Edmonton would lose the first game to the Flyers but would then take the next four to win their second straight Stanley Cup. Wayne Gretzky was awarded the Conn Smythe Trophy as the playoffs' most valuable player.