Oshie saw his production drop to 18 goals and 47 points in 72 games in 2017-18, but would play a crucial role in the Capitals 2018 Stanley Cup victory, scoring 8 goals (including 6 on the powerplay) and 21 points in 24 playoff games. On June 7, 2018, the Capitals defeated the first-year expansion Vegas Golden Knights in Game 5 of the 2018 Stanley Cup Final for their first Stanley Cup in franchise history. He is one of only 43 players to ever have 6 or more power play goals in a single playoffs.