The gritty forward lifted the trophy on the ice moments after the Blues beat Boston 4-1 in Game 7 of the Stanley Cup Final.
O'Reilly scored the opening goal late in the first period. It was the fourth straight game he notched a goal. He's the first player since Wayne Gretzky to score in four consecutive Stanley Cup Final games.
O'Reilly had just three goals in his first 22 postseason games.