Brashear, a rugged winger known more for his fighting than his skating, had gone 37 games without a goal before giving Washington a 3-2 lead. After teammate Karl Alzner drove the puck off the backboards, it bounced crazily toward the crease. Brashear tapped it into the net before goalie John MacDonald could smother it.
Eric Fehr added a power-play goal with 3:46 to go, and Nicklas Backstrom scored into an empty net with 50 seconds remaining.
Alex Ovechkin had a goal and two assists, and Viktor Kozlov also scored for the Capitals, who snapped a two-game skid.
Washington was without several injured sharpshooters, including Alexander Semin, Sergei Ferorov, Mike Green and Tom Poti. The Capitals received no sympathy from the Islanders, whose injury list included goalie Rick DiPietro, center Nate Thompson and defenseman Radek Martinek.
Mark Streit and Trent Hunter scored for New York, which wasted a 42-save performance by MacDonald.
Power-play goals by Ovechkin and Kozlov in a 76-second span provided Washington with a 2-0 lead, but New York countered with the extra man to get within a goal at the end of the first period.
Ovechkin took a pass from Milan Jurcina, skated to the middle of the left circle and unleashed a wrist shot that whizzed past MacDonald. Kozlov then deflected a shot by Bryan Helmer into the net.
Streit beat Brent Johnson on the glove side with a straight-on wrist shot from just inside the blue line.
Early in the second period, Chris Campoli of the Islanders appeared to tie it with a long-range goal off a faceoff. But the score was disallowed because it deflected off the skate of linesman Tony Sericolo.
Later in the period, with the teams playing 4-on-4, Washington's Keith Aucoin was denied by MacDonald on a breakaway. Aucoin had been recalled from Hershey earlier in the day after leading the AHL in scoring.
New York then pulled even when Washington's Sami Lepisto fell down behind the Capitals net while trying to control the puck. Andy Sutton swooped in and flipped a quick pass to Hunter, whose team-high 11th goal tied it.
Notes: The Islanders were the only Eastern Conference team that Washington coach Bruce Boudreau had not defeated. He's 1-0-2 against New York. ... Hunter (4 goals, three assists) has points in five of the last six games. ... Ovechkin has 14 goals and 20 assists in 24 games.
