Marty Walsh was one of the few players on the roster of the great Ottawa Senators teams of 1909 to 1911 who was not born in that city. He was born in Kingston, and played his early hockey with Queen's University where the team won the Intercollegiate Union title in 1906 and mounted an unsuccessful challenge against the Ottawa Silver Seven for the Stanley Cup. He turned pro with the Canadian Soo of the IHL in 1906-07 but broke his leg during the year and appeared in only seven games of the 24-game schedule before joining the Senators the following year. In his first year with Ottawa, he led the league with 27 goals in nine games, including a seven-goal outburst against Montreal on March 7, 1908.
He added to his records the following season by scoring 42 goals in just 12 games as the Senators went on to capture the Stanley Cup as champions of the ECHA with a 10-2-0 record. Walsh scored six goals in a 12-3 opening game victory against Galt in the Cup challenge of January 5 and 7, 1910 as Ottawa went on to a two-game, total-goals victory by a margin of 15-4. The Senators made another successful Cup defense later in the same month, this time against Edmonton, but lost the sacred bowl to the Montreal Wanderers because Montreal won the 1909-10 NHA title.
The Senators were back as Cup holders the following season after having won the NHA crown and assuming the title from the Wanderers. Ottawa defended its title against a challenge from Port Arthur in March 1911 by a two-game score of 21-8. In the second game of the series, played on March 16, 1911 in Ottawa, Walsh scored an amazing ten goals in the Senators 14-4 victory.
Marty Walsh was inducted into the Hockey Hall of Fame in 1962.