Washington rallied late in regulation to force overtime, with Nic Dowd pulling the Capitals within a goal with 6:38 remaining and Conor Sheary tying it with 3:47 left.
Hischier gave New Jersey a 3-1 lead 22 seconds into the second period.
Mackenzie Blackwood made 27 saves for the Devils. Ilya Samsonov stopped 33 shots for the Capitals.
Alain Nasreddine directed the Devils for the second straight game. Coach Lindy Ruff tested positive for COVID-19 before Friday’s game.
New Jersey won its third straight overall, beating Washington for the first time since Feb. 22, 2020.
NOTES: Washington F Nicklas Backstrom and F T.J. Oshie were out with non-COVID-19 illnesses. Backstrom has played just three games this season. … The Capitals sent F Aliaksei Protas to Hershey of the AHL. … New Jersey D Dougie Hamilton was hit in the face with a puck in the first period and did not return.
Devils: Host Boston on Tuesday night.
Capitals: At St. Louis on Friday night.