The 39-year-old Numminen underwent corrective heart surgery in September on a faulty valve.
"He's cleared to practice with the team and based on what I watched out there he looked pretty good," General Manager Darcy Regier said on the team's Web site after a practice before Friday's contest at Washington. "It's a good start and we're excited. Teppo brings a wealth of experience and stability (and) I think he definitely impacts our defense with regard to stabilizing and settling things down."
Coach Lindy Ruff said the veteran defenseman has been a big part of the team.
"I think just for the guys to see him around, your initial thought is you are happy for him," said Ruff.
Numminen has missed the Sabres' first 29 games this season and his return to game action is undetermined.