The 1974–75 NHL season was the 58th season of the National Hockey League. Two new teams, the Washington Capitals and Kansas City Scouts were added, increasing the number of teams to 18. To accommodate the new teams, the NHL re-organized its divisional structure and playoff format. The regular season was expanded to 80 games per team (which would be the case until 1992–93). The Philadelphia Flyers won the Stanley Cup for the second consecutive year.

With the addition of two new teams, the Washington Capitals and Kansas City Scouts, the NHL bumped up the number of games from 78 to 80 and split the previously two-division league into four divisions and two conferences. Because the new conferences and divisions had little to do with North American geography, geographical references were also removed until 1993. The East Division became the Prince of Wales Conference and consisted of the Adams Division and Norris Division. The West Division became the Clarence Campbell Conference and consisted of the Patrick Division and Smythe Division. The Capitals had the worst season ever recorded in the history of major professional hockey, and the third worst in the postwar era the following season, while the Scouts the following season would have the fifth worst record of the postwar era.

The Clarence Campbell Bowl and Prince of Wales Trophy (previously awarded to the first-place finishers of the West Division and East Division respectively) are now awarded to the first-place finishers of the Campbell Conference and the Wales Conference respectively.

In early 1975, newspapers reported that the California Golden Seals and Pittsburgh Penguins were to be relocated to Denver and Seattle respectively, in an arrangement that would have seen the two teams sold to groups in those cities that had already been awarded "conditional" franchises for the 1976–77 season. After staunchly rejecting previous franchise relocation attempts, league president Clarence Campbell saw this as a method by which the NHL might extricate itself from two problem markets, while honoring the expansion commitments it had made. The Penguins ended up staying in Pittsburgh (and ultimately, over time, made Pittsburgh one of the NHL's stronger markets),^[1][2] while the Golden Seals would move to Cleveland in 1976 to become the Cleveland Barons before merging with the Minnesota North Stars in 1978. The Scouts gave up on Kansas City after two seasons and moved to Denver to become the Colorado Rockies in 1976 before moving east to East Rutherford, New Jersey in 1982 and becoming the New Jersey Devils; Denver would return to the NHL in 1995 when the Quebec Nordiques moved there and became the Colorado Avalanche, where they remain to this day. Seattle would be again awarded a expansion team in 2018 to begin play in 2021.

For the first time ever in the National Hockey League, there was a three-way tie for first place overall. The respective divisional leaders of the Norris (Montreal Canadiens), Patrick (Philadelphia Flyers), and Adams (Buffalo Sabres) all had 113 points. By virtue of having the most wins, the Flyers were accorded the league's best record and held home-ice advantage in the playoffs, where they eventually met the Sabres in the Stanley Cup Finals.

The Vancouver Canucks, which had been playing in the original East Division since they debuted in the league, were moved over to the Campbell Conference and led the way in the Smythe Division with a meager 86 points.

Bobby Orr won the scoring title for the second time, the only defenseman in the history of the NHL to accomplish this feat.

The surprise team of the year were the Los Angeles Kings. When the new divisional lineup was announced, many hockey experts felt the Canadiens were in the weakest division and joked they would clinch first place by Christmas. But the Kings, with their disciplined defensive style, and excellent goaltending tandem of Rogie Vachon and Gary Edwards, battled Montreal all year for first place. The Kings opened their season by beating the defending champion Philadelphia Flyers in Philadelphia and tying the Canadiens in Montreal. The Kings lost only twice in their first 26 games, and on Christmas, Montreal had only a two-point lead in the standings. When L.A. won in Montreal in mid-January, they were back in first place. The teams continued to battle, with the Canadiens finally clinching first place with three games to play.

Note: GP = Games played, W = Wins, L = Losses, T = Ties, Pts = Points, GF = Goals for, GA = Goals against

Note: Teams that qualified for the playoffs are highlighted in bold

With the new conference and division structure, the 1975 playoffs used a new format. The playoffs were expanded from 8 to 12 teams with the top 3 teams in each division qualifying for the playoffs. The first place teams in each division earned a first round bye, while the second and third place teams were seeded 1–8 based on their regular season record and played a best-of-three series. The four division winners then joined the 4 preliminary series winners in the quarterfinals, and they were again re-seeded 1–8 based on regular season record. This re-seeding took place again in the semifinals, with the teams seeded 1–4. Proponents of this re-seeding state that it makes the regular season more important by rewarding teams with better records with potentially easier matchups. In addition, it avoids the potential issue of two lower seeded teams (who may have pulled early round upsets) playing each other in the next round while two higher seeded teams are playing each other (as is possible in a "bracketed" playoff format like in the NBA). The biggest beneficiary of this format was the Vancouver Canucks, who were ninth overall in the regular season but received a first-round bye for winning the relatively weak Smythe Division. Unfortunately for Vancouver, the fact that the second round was seeded without regard to their first place divisional finish meant they had to face another division champion in the second round, the Norris-winning Montreal Canadiens, who defeated Vancouver four games to one. The team that suffered the most from the new format, the Los Angeles Kings, had the 4th best overall record but had to play in the risky mini series where they were upset by the 12th-seeded Toronto Maple Leafs 2 games to 1.

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.

The Los Angeles Kings entered the Preliminary round as the top seed (and fourth seed overall) earning 105 points during the regular season. The Toronto Maple Leafs earned 78 points during the regular season and entered the Preliminary round as the eighth seed (and twelfth seed overall). This was the first playoff series between these two teams. Los Angeles won this year's season series earning 9 of 10 points during the regular season.

The Boston Bruins entered the Preliminary round as the second seed (and fifth seed overall) earning 94 points during the regular season. The Chicago Black Hawks earned 82 points during the regular season and entered the Preliminary round as the seventh seed (and eleventh seed overall). This was the fifth playoff series between these two teams, with Boston winning all four previous meetings. They last met in the 1974 Stanley Cup Semifinals where Boston won in six games. The teams split this year's regular season series.

The Pittsburgh Penguins entered the Preliminary round as the third seed (and sixth seed overall) earning 89 points during the regular season. The St. Louis Blues earned 84 points during the regular season and entered the Preliminary round as the sixth seed (and tenth seed overall). This was the second playoff series between these two teams, with St. Louis winning the only previous meeting. They last met in the 1970 Stanley Cup Semifinals where St. Louis won in six games. The teams split this year's regular season series.

The New York Rangers entered the Preliminary round as the fourth seed (and seventh seed overall) earning 88 points during the regular season, winning the tie-breaker with the New York Islanders in wins (37 to 33). The New York Islanders earned 88 points during the regular season and entered the Preliminary round as the fifth seed (and eighth seed overall), losing the tie-breaker with the New York Rangers in wins (37 to 33). This was the first playoff series between these two teams. The Rangers won this year's season series earning 7 of 12 points during the regular season.

The Philadelphia Flyers entered the playoffs as the defending Stanley Cup champions, the Patrick Division champions, the Clarence Campbell Conference regular season champions and the first seed overall earning 113 points during the regular season, winning the tie-breaker over both the Buffalo Sabres and Montreal Canadiens in total wins. The Toronto Maple Leafs were seeded eighth in the Quarterfinals as the lowest remaining seed in the playoffs and qualified for the Quarterfinals by defeating the Los Angeles Kings in the Preliminary round. This was the first playoff series between these two teams. Philadelphia won this year's season series earning 7 of 8 points during the regular season.

The Buffalo Sabres entered the playoffs as the Adams Division champions, the Prince of Wales Conference regular season champions and the second seed overall earning 113 points during the regular season, losing the tie-breaker to the Philadelphia Flyers in total wins, while winning the same tie-breaker over the Montreal Canadiens. The Chicago Black Hawks were seeded seventh in the Quarterfinals as the second lowest remaining seed in the playoffs and qualified for the Quarterfinals by defeating the Boston Bruins in the Preliminary round. This was the first playoff series between these two teams. Buffalo won three of the four games in this year's regular season series.

The Montreal Canadiens entered the playoffs as the Norris Division champions and the third seed overall earning 113 points during the regular season, losing the tie-breaker to both the Philadelphia Flyers and Buffalo Sabres in total wins. The Vancouver Canucks earned 86 points during the regular season and entered the playoffs as the Smythe Division champions. The Canucks were seeded sixth in the Quarterfinals as the third lowest remaining seed in the playoffs and qualified for the Quarterfinals by winning their division. This was the first and to date only playoff series between these two teams. Montreal swept all four games in this year's regular season series. This series also marked the first appearance of a team representing Vancouver in the Stanley Cup playoffs in 51 years. The most recent team to represent Vancouver prior to this was the Vancouver Maroons who lost to the Montreal Canadiens in the 1924 Stanley Cup Semifinals.

The Pittsburgh Penguins entered the Quarterfinals as the fourth seed and they qualified for this round by defeating the St. Louis Blues in the Preliminary round. The New York Islanders were seeded fifth in the Quarterfinals and qualified for this round by defeating the New York Rangers in the Preliminary round. This was the first playoff series between these two teams. The teams split this year's regular season series. After trailing the series 3–0, the Islanders rallied to win four straight games and take the series. They became the second North American professional sports team (after the 1942 Toronto Maple Leafs) to accomplish such a feat.

This was the first playoff series between these two teams. The Flyers won this year's season series earning eight of twelve points during the regular season. After becoming the second North American professional sports team to win a best-of-seven series after trailing 3–0 in the previous round against the Penguins, the Islanders almost accomplished the same feat in this round. However, the Flyers firmly defeated them in game seven to preserve the series win.

This was the second playoff series between these two teams, with Montreal winning the only previous meeting. They last met in the 1973 Stanley Cup Quarterfinals where Montreal won in six games. Buffalo won this year's season series earning nine of ten points during the regular season.

This was the Philadelphia Flyers' second consecutive Stanley Cup Finals appearance and second overall. In the previous year's Stanley Cup Finals, the Flyers defeated the Boston Bruins in six games. This was the Buffalo Sabres' first Stanley Cup Finals appearance in their fifth season. This was the first playoff meeting between these two teams. The Buffalo Sabres won this year's regular season series earning seven of eight points.

In the first Stanley Cup Finals matchup between two expansion teams, The Philadelphia Flyers beat the Buffalo Sabres four games to two for their second consecutive Stanley Cup.

Source: NHL.^[4]

Note: GP = Games played; G = Goals; A = Assists; Pts = Points

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 1974–75 (listed with their first team):

The following is a list of players of note that played their last game in the NHL in 1974–75 (listed with their last team):

NOTE: Ullman would finish his major professional career in the World Hockey Association.