Laich, who has totaled 234 points in his NHL career, has been a part of the Capitals organization since 2004. The 28-year-old played in every game last year, totaling 48 points.
"I'm thrilled to make the commitment to remain a Capital," Laich said in a statement released by the team. "It is a wonderful organization with terrific fans and I'm very happy to continue to call Washington home for many years to come."
Dupuis' deal is reported to be worth $2 million. Last year, the 32-year-old forward played in 81 games and totalled 37 points while finishing plus-16.