Brouwer, 27, will earn $3.6 million in 2013-14, $3.65 million in 2014-15 and $3.75 million in 2015-16.
"Troy is a physical and versatile power forward who can play both wings and who has averaged close to 20 goals in the past three seasons," general manager George McPhee said.
"He is a Stanley Cup winner and a great leader."
Brouwer had 18 goals and 15 assists in 82 games with the Capitals last season.
The 6-foot-3 (190.5cm), 213-pound (615.2kg) Brouwer helped the Chicago Blackhawks win the 2010 Stanley Cup while amassing four goals and four assists in 19 playoff games.