Washington sent a 2019 third-round pick and a conditional 2020 sixth-round pick to Los Angeles.
"We are pleased to welcome Carl to our organization," general manager Brian MacLellan said. "We felt this trade enables us to add depth up front and provides us with a veteran player with a tremendous amount of speed to help us on the penalty kill."
Hagelin must satisfy a games-played requirement in the playoffs and the Capitals must win two rounds for the Kings to get the sixth-rounder in next year’s draft.
The teams announced the trade after Washington winger Devante Smith-Pelly cleared waivers and was assigned to Hershey of the American Hockey League. The Capitals needed to wait until Smith-Pelly was claimed or cleared waivers to clear a roster spot and salary-cap space for Hagelin. The Kings still had to retain salary for the Capitals to fit in Hagelin’s $4 million salary.
Hagelin has just two goals and six assists in 38 games this season with Pittsburgh and Los Angeles. But the Capitals are plenty familiar with Hagelin after facing him in the playoffs the past six years.
Washington is Hagelin’s fifth team during his eight-year NHL career. He has 230 points in 526 regular-season games and won the Stanley Cup with the Penguins in 2016 and 2017.