Alexander Ovechkin and Matt Pettinger also scored for Washington. Ovechkin has six goals in his last five games. Nathan Horton scored for the Panthers, who have lost four in a row.
Zubrus' first goal came during a five-on-three power play in the third period. His wrist shot from the right circle got past goaltender Alex Auld on the glove side at 14:15 for a 3-1 lead.
Zubrus added an empty-net goal with 30 seconds left.
Florida tied it at 1 on Horton's power-play goal at 5:05 of the second. Jay Bouwmeester made a cross-ice pass to Horton, whose wrist shot from the right circle beat Kolzig.
The Capitals regained the lead about 90 seconds later on Ovechkin's goal. His shot from just outside the crease was blocked by Auld, but Ovechkin poked in the rebound.
Washington took a 1-0 lead at 18:03 of the first period. Pettinger took a shot from in front and his momentum pushed him into Auld. Pettinger's skate hit the puck and helped it into the net, and a video review confirmed the goal.
It was the fourth win in five games for the Capitals. Florida has lost 11 of its last 14.
Notes: The Capitals held an opponent to less than two goals for the second time this season. ... Florida's Stephen Weiss missed the game with a sore knee.