Lukaku has not started a league game since picking up an injury in October and missed the last two games after testing positive for COVID-19.
But the Belgian transformed his team’s display after coming on at halftime at Villa Park, providing a constant threat, putting his side ahead and then earning the late penalty that secured the three points for Thomas Tuchel’s side.
Third-placed Chelsea, who had drawn with Everton and Wolverhampton Wanderers in their previous two games, are now level with second placed Liverpool on 41 points — six behind leaders Manchester City.
Villa had taken the lead in the 28th minute with some good fortune when Matt Targett’s cross struck the head of Chelsea defender Reece James and flew past goalkeeper Edouard Mendy.
The visitor’s drew level six minutes later, though, when Matty Cash clumsily brought down Callum Hudson-Odoi inside the box and Jorginho coolly converted the penalty.
Halftime substitute Lukaku made a swift impact, getting in front of Tyrone Mings to angle in a fine, glancing header from a Hudson-Odoi cross to put Chelsea ahead in the 56th minute.
Mason Mount should have added a third but shot wide after Villa keeper Emiliano Martinez had raced out of his area and failed to clear.
Hudson-Odoi should also have done better when he was found in space at the back post but his shot was comfortably dealt with by Martinez.
In stoppage time, Lukaku powered his way from his own half before he was brought down inside the box by Villa defender Ezri Konsa. Jorginho again made no mistake to secure three points.
“I needed a performance like this,” said Lukaku, “It’s been difficult getting (on at) the end of games. I kept working hard. I’m happy with my performance and have to push on,” he added.
The former Manchester United and Inter Milan striker said Chelsea remained in the race to catch leaders City.
“We are the hunters now. The last results were not the best and now we have to chase. We have to treat every game like a final. Today we won and now we have to push on,” he said.