Samaras had been out since suffering a torn hamstring in the 4-1 win over Kilmarnock at Parkhead back on January 30.
However, the Greek forward returned to the Hoops starting line-up in the league meeting with Well at Fir Park on Wednesday night.
And the 6ft 3in star headed home a James Forrest cross in the second half to briefly get the Glasgow club back on level terms.
Having the 28-year-old available once again will boost Celtic's chances of getting results in their next two fixtures greatly.
They take on St Mirren in the quarter-final of the William Hill Scottish Cup in Paisley tomorrow and then travel to Italy next week for their Champions League rematch with Juventus.
But Lennon has revealed he was far from impressed with Sami's play in the disappointing 2-1 loss to Motherwell and has called on him to raise his game.
He said: "I'm pleased to see Sami back, but I wasn't delighted with his overall performance. He can do more. He should do more.
"He got his goal so that was a positive. There were good aspects of his play, particularly in the second half.
"I don't think he is lacking in confidence. He has been an important player for us this season. But he can certainly play better than he did.
"I was delighted with James Forrest's performance. Thomas Rogne got another good 90 minutes. But I was disappointed with some others. We must do better."
Lennon started the game with Beram Kayal and Tom Rogic in the Celtic central midfield – but substituted both of them in the second half.
The Scottish champions performed far better with Joe Ledley and Victor Wanyama in the boiler room towards the end of the game. But the Hoops manager has absolved Australian signing Rogic, who showed his potential with some fine touches, of any blame for the frustrating reverse.
He explained: "Tom is a young lad and has only had a couple of games in the first team.
"Playing against Motherwell was a great learning experience for him.
"He is the least of my problems from the other night.
"His run-out will have done him the world of good.
"It will have helped him get acquainted with the demands of the Scottish game. But when we went with Joe and Victor in midfield we looked particularly strong."