Washington, DC – Ruslan Fedotenko scored two goals and the 3, on Friday.
Marian Gaborik, Artem Anisimov, Brian Boyle and Brad Richards also scored for the Rangers, who snapped a two-game losing streak to win for the eighth time in their last 10.
Henrik Lundqvist made 18 saves and New York went 2-2 on its four-game road trip.
Alex Ovechkin, Troy Brouwer and John Carlson scored for the Capitals, who went 2-1 on a three-game homestand. They are just 3-6-1 in their last 10. Michal Neuvirth allowed six goals on 33 shots in the loss.
After losing four in a row to Washington, the Rangers have won the past four meetings by a combined score of 21-4.