During the 2016–17 season, on January 20, 2017, Copley was recalled from the Chicago Wolves of the AHL by the Blues. He made the first start of his NHL career on January 21 against the Winnipeg Jets, where the Blues lost 5–3. After he was returned to the Wolves, on February 27, 2017, Copley was traded back to the Capitals in a deadline trade along with Kevin Shattenkirk in exchange for Zach Sanford, Brad Malone, a 2017 first-round pick, and a conditional second-round pick in 2019. Copley was called up to the NHL during the Capitals 2018 Stanley Cup playoffs run and although he did not play during the playoffs, he stayed with the team as they won the 2018 Stanley Cup.