Ovechkin's score -- his NHL-leading 41st of the season -- came with 4:17 remaining and boosted the Capitals to a third straight win.
The Russian superstar also recorded a pair of assists and Troy Brouwer netted two power-play goals for Washington.
Braden Holtby turned aside 30 shots.
Brad Boyes scored twice while Tomas Fleishmann and Jimmy Hayes each added a goal for the Panthers, who fell for the sixth time in seven games.
Tim Thomas made 27 stops.
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