The 1919 Stanley Cup Finals was the ice hockey playoff series to determine the 1919 Stanley Cup champions. The series was cancelled due to an outbreak of Spanish flu after five games had been played, and no champion was declared. It was the only time in the history of the Stanley Cup that it was not awarded due to a no-decision after playoffs were held.

The Stanley Cup is the championship trophy awarded annually to the National Hockey League (NHL) playoff champion. It is the oldest existing trophy to be awarded to a professional sports franchise in North America, and the International Ice Hockey Federation (IIHF) considers it to be one of the "most important championships available to the sport". The trophy was commissioned in 1892 as the Dominion Hockey Challenge Cup and is named after Lord Stanley of Preston, the Governor General of Canada, who donated it as an award to Canada's top-ranking amateur ice hockey club. The entire Stanley family supported the sport, the sons and daughters all playing and promoting the game. The first Cup was awarded in 1893 to the Montreal Hockey Club, and winners from 1893 to 1914 were determined by challenge games and league play. Professional teams first became eligible to challenge for the Stanley Cup in 1906. In 1915, the National Hockey Association (NHA) and the Pacific Coast Hockey Association (PCHA), the two main professional ice hockey organizations, reached an agreement in which their respective champions would face each other annually for the Stanley Cup. It was established as the de facto championship trophy of the NHL in 1926 and then the de jure NHL championship prize in 1947.