The 1977–78 NHL season was the 61st season of the National Hockey League. The Montreal Canadiens won their third Stanley Cup in a row, defeating the Boston Bruins four games to two in the Stanley Cup Finals.

Clarence Campbell retired as NHL President, prior to this season. John Ziegler succeeded him.

A trophy for the top defensive forward, the Frank J. Selke Trophy, made its debut this season and went to Bob Gainey, who played left wing for Montreal.

On June 14, 1978, the league approved the merger of the financially struggling Cleveland Barons and Minnesota North Stars franchises, reducing the number of teams to 17, with the North Stars (now the Dallas Stars) assuming the Barons' place in the Adams Division. It was the only instance of a league franchise to dissolve since the Brooklyn Americans ceased operations in 1942. The next time the NHL had a team in Ohio would be the expansion Columbus Blue Jackets in the 2000–01 season.

The league changed the playoff qualification format for this season. Whereas before the first through third-place teams in every division qualified, the format was changed to only guarantee the first and second-place finisher in each division a playoff spot. The last four qualifiers were from the next-best four regular-season records from third and lower place finishers.

Teams were required to place the last names of players on the back of all jerseys starting with this season, but Toronto Maple Leafs owner Harold Ballard initially refused, fearing that he would not be able to sell programs at his team's games. The NHL responded by threatening to levy a fine on the team in February 1978, so Ballard complied by making the letters the same color as the background they were on, which for the team's road jerseys was blue. The League threatened further sanctions, and despite playing more than one game with their "unreadable" sweaters, Ballard's Maple Leafs finally complied in earnest by making the letters white.^[1]

Bobby Orr sat out the season to rest his oft-injured knee in the hope that rest would allow him to return to play in 1978–79.

On December 11, 1977, the Philadelphia Flyers' Tom Bladon became the first defenseman in NHL history to score eight points in one game.^[2] He scored four goals and four assists versus the Cleveland Barons. It was 25% of his point total for the entire season.

The Colorado Rockies qualified for the playoffs for the first and only time in franchise history. They would not make the playoffs again until after the team had moved to New Jersey, in 1988. The next time the playoffs came to Colorado would be the Colorado Avalanche's championship season of 1996.

GP = Games Played, W = Wins, L = Losses, T = Ties, Pts = Points, GF = Goals For, GA = Goals Against, PIM = Penalties In Minutes

Teams that qualified for the playoffs are highlighted in bold

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The playoffs were held in four rounds, preliminary, quarterfinals, semifinals and final. In the preliminary round, the Detroit Red Wings were the only lower-placed team to win over the higher-placed team. The Red Wings were then defeated in five games by the first-place Montreal Canadiens. The Toronto Maple Leafs defeated the Los Angeles Kings to advance to the quarterfinals, where the Leafs upset the third-place New York Islanders in seven games, setting up an "Original Six" playoff against Montreal. The upsets ended there as the Canadiens swept the Leafs to advance to the final. In the other groupings, the higher-placed team won each round, and the second-place Boston Bruins advanced to the final to playoff against the first-place Canadiens. In the final, the Canadiens defeated the Bruins in six games to win their third consecutive Stanley Cup.

The Colorado Rockies made their one and only playoff appearance in the preliminary round against the Philadelphia Flyers, and were swept in two games. It would take another ten years before they got to the playoffs again in New Jersey. The Chicago Black Hawks were swept in the other "Original Six" matchup of the playoffs, losing to Boston in the quarterfinals.

The twelve teams that qualified for the playoffs are ranked 1–12 based on regular season points.

Note: Only teams that qualified for the playoffs are listed here.

Game 4 was the final playoff game at the Detroit Olympia

Game five was Fred Shero's last game as head coach of the Flyers, and Gerry Cheevers left the ice without shaking hands with any of the Flyers.^[4]

The league introduced the Frank J. Selke trophy this season. It rewards the forward judged to be the best at defensive abilities.

GP = Games Played, G = Goals, A = Assists, Pts = Points, PIM = Penalties In Minutes

Source: NHL.^[5]

Note: GP = Games played; Min – Minutes Played; GA = Goals Against; GAA = Goals Against Average; W = Wins; L = Losses; T = Ties; SO = Shutouts

The following is a list of players of note who played their first NHL game in 1977–78 (listed with their first team, asterisk(*) marks debut in playoffs):

Nedomansky began his major professional career in the World Hockey Association.

The following is a list of players of note that played their last game in the NHL in 1977–78 (listed with their last team):

NOTE: Goldsworthy and Neilson would finish their major professional careers in the World Hockey Association.