The NHL's reigning MVP and last season's leading scorer was among the first few players on the ice at the team's practice facility, out there with coach Bruce Boudreau about 15 minutes before the full session began.
Ovechkin missed two games while he was gone, ending a 2½-season consecutive games streak.
"When you have somebody for 203 straight games, and then you miss somebody of his stature, when he comes back it's like your big brother's back," Boudreau said. "You're happy to see him. And you're happy to see him smiling again."
Ovechkin thanked Capitals general manager George McPhee for letting him leave the team to be with his mother's father, who helped raise Ovechkin.
"It shows you how good people [they are] here -- how they love me, how they respect me and how they respect my family," Ovechkin said.
He broke the league record for goals by a left wing with 65 last season, helping Washington win the Southeast Division title. He is off to a slow start this season, with only two goals and five points.
The Russian hasn't scored a goal in his past six games, and he acknowledged Monday his grandfather's health was weighing on him.
Being away "helped me a lot," Ovechkin said.
He skated with a team of teenagers to keep in shape while in Moscow.
"It was a great decision for him to go home, because family comes first and obviously you don't want to miss those opportunities when you look back on them in life," Capitals captain Chris Clark said. "We're obviously glad to have him back and hopefully he can put some of that behind him during the game. He's the best player in the world, and we're happy to have him on our team."