Carbery, who is 41 years old, has been with Toronto for the last two seasons. He played his last two seasons of his professional career with the Capitals' minor league affiliate, the South Carolina Stingrays, and coached the team from 2011 to 2016.
Spencer Carbery returned later to coach the Capitals' AHL affiliate, the Hershey Bears, in 2018. He led the team to the Macgregor Kilpatrick Trophy, which is the league's regular-season championship in 2021.
He was also named coach of the year that season.
In the last two years, Toronto had 54 and 50 wins. They lost in the first round of the NHL playoffs in 2021-22 and then in the second round this season.
Carbery, who played left wing, had a four-year career as a professional player, including his last four seasons in the ECHL.
He won an ECHL championship with the Stingrays in 2009. He had 19 points that season, including 12 goals.
The Capitals fired coach Peter Laviolette in April after they missed the playoffs for the first time since 2014.
Laviolette had a record of 115-78-27 in three years as the Capitals' coach.
After it won the Stanley Cup in 2018, Washington lost in the first round for four consecutive seasons.
The Capitals were arguably the NHL's best team from 2008-09 to 2016-17, when left winger Alex Ovechkin was as the peak of his career.
He is now 37 years old and will be led by his eighth coach.