The 32-year-old center is in the final season of a 10-year deal he signed with the Capitals in 2010. He negotiated his new pact without the help of an agent, according to Sportsnet's Chris Johnston.
Backstrom has been a staple in the Capitals' lineup since the club drafted him fourth overall in 2006. He's amassed 908 points (240 goals) in 934 career games with Washington, good for second in franchise history.
An integral member of the Capitals' Stanley Cup-winning team in 2018, Backstrom is in the midst of another great season, posting nine goals and 35 points in 39 games.
His new contract will take him through the 2024-25 season, his age-37 campaign.