The 1918–19 Ottawa Senators season was the club's 34th season, second in the National Hockey League (NHL), and they would see much improvement over the previous season. The season was cut short by the Toronto Arenas suspending operations, leaving the Senators and Montreal Canadiens to play the first best-of-seven playoff series to determine the NHL championship, won by Montreal.

Team business

The club's ownership and arena arrangements changed in the off-season. Prior to the season, Ted Dey, as arena owner, held out the use of The Arena in negotiations with the Ottawa Hockey Club, of which he was one-third partner. Martin Rosenthal and Tommy Gorman, his hockey club partners, tried to use the Aberdeen Pavilion again. Meanwhile, Dey signed an agreement with Percy Quinn, who held an option on the Quebec city hockey club to rent The Arena for a new 'Canadian Hockey Association' league. This however was a ruse. However, his ruse worked to his advantage in negotiating with the Ottawa HC. When it became clear that the Aberdeen would not be converted back to hockey, Rosenthal gave up his share of the hockey club. As part of an agreement reached out, Dey and Gorman now became equal partners in the new 'Ottawa Arena Club' which would operate the Ottawa hockey club in the NHL. The Ottawas were now bound to the Arena for the next five years as well. Rosenthal was provided $500 as compensation for his share. Dey was sued by Percy Quinn for his actions and trial took place in December 1918 and January 1919 in Toronto. Quinn lost his legal case as the option on the Arena was not enough of a contract to prove legal fraud on Dey's part, who continued to offer a place in the Arena to Quinn. By this time, Quinn's proposed league had failed as the players had signed with Dey and Gorman and elsewhere with the NHL.

Regular season

Senators player Hamby Shore would die of pneumonia before the season began on October 14, 1918. He was a victim of the influenza epidemic that spread across North America from 1918 to 1919. Shore was 32 years old. After a 5–5–0 record in the first half of the season, the Senators would go on to a 7–1–0 record in the second half. Cy Denneny and Frank Nighbor would lead the team with 18 goals and 22 points each, while Clint Benedict would win a league best 12 games, along with his NHL leading 2.91 GAA. After the season, the club travelled to Vancouver to play a best-of-three against the Millionaires, winning the exhibition series three games to two.

December

The Senators finished December with a 2-1-0 record, earning four points. Ottawa was tied with the Canadiens for first place in the NHL.

January

At the end of January, the Senators had a perfect 3-0-0 record to start the second half of the season, earning six points and sitting in first place in the NHL standings.

February

Ottawa finished the second half of the season with a 7-1-0 record, earning 14 points and finishing in first place. The club would qualify for the playoffs, as they would face the Montreal Canadiens for the NHL championship.

Final standings

Record vs. opponents

Schedule and results

Playoffs

Ottawa would face the Montreal Canadiens, winners of the first half of the NHL season, in a best-of-seven series, deciding who would represent the NHL at the 1919 Stanley Cup Finals.

Playing stats

Scoring leaders

Goaltending

Transactions

The Senators were involved in the following transactions during the 1918–19 season.

Trades

Free agents

Released