Beginning in 1923, he played centre for three National Hockey League (NHL) teams: the Montreal Canadiens (in two stints), the Chicago Black Hawks, and the New York Rangers.

[7] Dan's son, Blake, played with the University of Wisconsin and won the Hobey Baker Award as best collegiate player in 2010.

[12] His performance in the Memorial Cup tournament earned him an invitation to play for the Stratford Indians, a senior league team, for the 1921–22 season.

[11] During a CNR hockey tournament held in December 1922 in Montreal, Morenz scored nine goals in a game for Stratford.

[16] However, in July Dandurand learned that Morenz and his father had been in contact with the Toronto St. Patricks, a rival team in the NHL.

He wrote a letter in August to Dandurand, explaining that he could not leave Stratford, and included the cheque given to him as a signing bonus.

He scored another goal in the second game, as Montreal defeated the Tigers 3–0 to win their second Stanley Cup championship and Morenz's first with the team.

That was followed with seven goals and eight points in six playoff games, as Montreal lost in the Stanley Cup Finals to the Victoria Cougars of the WCHL.

Morenz tied with linemate Aurèle Joliat in leading the Canadiens in scoring in 1925–26 with 26 points, finishing fifth in the league.

The one goal he scored in four playoff games was a series winner in the quarter-finals, eliminating the Montreal Maroons from postseason contention.

[19] He was also named to the newly created NHL All-Star team, being selected as the first-team centre, as the top player in that position.

[28] In the playoffs, the Canadiens reached the Stanley Cup Finals for the second consecutive year, playing the Chicago Black Hawks.

With 49 points he finished third in league scoring, and became the first player in NHL history to win the Hart Trophy for a third time, also being named to the first All-Star team again.

After returning to the team, Morenz was unable to play at his previous level, and the Canadiens' fans began booing him.

[31] With the decline in production, reports of the Canadiens wanting to trade Morenz began appearing in Montreal newspapers.

Adding to Morenz's concern was the lack of response from either of the Canadiens' owners, Léo Dandurand or Joe Cattarinich, informing him of what was happening.

After 23 games with the Black Hawks, in which he scored 15 points, Morenz was traded for the second time in his career; he was sent to the New York Rangers on January 26, 1936, for forward Glen Brydson.

[3] The Canadiens spent most of the 1936–37 season as one of the best teams in the NHL; Morenz contributed regularly, occasionally showing the speed that had made him notable at the start of his career.

In the first period, Morenz went after the puck in the Chicago end while being chased by Black Hawks defenceman Earl Seibert.

Morenz lost his balance and fell to the ice, crashing into the boards and catching his left skate in the wooden siding.

[36] Helped to the Canadiens bench by his teammates, Morenz was taken to Hôpital St-Luc, where it was found that his leg was fractured in four places.

[39] While recovering in the hospital, Morenz received many get-well cards and visits from his teammates and players from other NHL teams.

[41] The Canadiens were scheduled to play the Montreal Maroons the evening of March 9, a game the NHL offered to cancel in honour of Morenz's death.

The players on the Canadiens and Maroons wore black armbands for the game, and prior to the start, two minutes of silence were observed in his honour.

Fans were allowed to file past the casket, laid at centre ice, and 50,000 people paid their respects.

[13] A 1950 Canadian Press poll named Morenz the best ice hockey player of the first half of the 20th century.

[51] Through his exciting play, Morenz encouraged the expansion of the NHL, helping bring professional hockey to the United States.

[52] Boxing promoter Tex Rickard, owner of Madison Square Garden, also saw Morenz play early in his career and agreed to add ice to his building for an NHL team known as the New York Americans.

[53] Morenz's daughter Marlene married Bernie Geoffrion, who also played for the Canadiens and Rangers, and was later inducted into the Hockey Hall of Fame.

When the Canadiens retired Geoffrion's number on the night of his death on March 11, 2006, the team recognized the link between the two men.