The 1912–13 NHA season was the fourth season of the National Hockey Association (NHA). Six teams played 20 games each. The Quebec Bulldogs won the league championship to retain the Stanley Cup. They played and defeated the Sydney Millionaires in a challenge after the regular season.
The Arena Gardens was completed in Toronto and the two dormant NHA franchises started play as the Toronto Hockey Club ('Torontos' or 'Blue Shirts') and the Toronto Tecumsehs ('Indians'). The Arena Gardens hosted a pre-season exhibition match between the Montreal Canadiens and Montreal Wanderers, at which a brawl broke out and Sprague Cleghorn would be charged with assault.
For this season the NHA teams played again with six skaters, abandoning the position of rover. It was agreed that from February onwards, the teams would play with seven. However, after several games at the start of February played with the rover, the decision was made to abandon the rover position permanently.
The Stanley Cup trustees decided prior to this season that all future Stanley Cup challenges would take place after the end of the regular season.