Ovechkin gave the Capitals a 2-0 lead at 3:12 of the second period when he entered the offensive zone and beat Daniil Tarasov with a wrist shot from the right circle.
"Yeah, it's a pretty cool number," Ovechkin said. "Just keep going. Move on."
The forward became the fourth player to score at least 20 goals in each of his first 17 NHL seasons and trails Jaromir Jagr by 16 goals for third in NHL history.
Aliaksei Protas and Garnet Hathaway scored, and Ilya Samsonov made 17 saves for the Capitals (15-4-6).
"Defensively, I thought we were really strong," Washington coach Peter Laviolette said. "Sometimes we shot ourselves in the foot by throwing the puck away, but, for the most part, I thought it was pretty good offensively as well."