Two incidents stand out in Stewart’s umpiring career. He was the plate umpire at Brooklyn the night Johnny Vander Meer of Cincinnati pitched his second consecutive no-hitter on June 15, 1938. And as the second base umpire in the first game of the 1948 WS, Stewart made a controversial safe call on the Braves Phil Masi when Bob Feller and Lou Boudreau tried a pickoff play; Masi later scored the only run of the game.
In addition to his work as a baseball umpire, Stewart served nine years as a referee in the NHL. During the 1937-38 hockey season, he coached the Chicago Black Hawks to a Stanley Cup championship. He also coached the hockey team at M.I.T. for seven years.