The 20-year-old striker scored the opening goal at Villa Park with a clinical first-time finish after 68 minutes and was only denied in the first period by a fine reaction save from Brad Guzan.
The Belgian comfortably outperformed compatriot Christian Benteke, who missed a seventh-minute penalty on his return to the Villa side, and now has five goals in as many Barclays Premier League appearances for the Toffees.
"We want him to fulfil his potential and he has got a terrific potential to fulfil. That's what the parent club want too - for him to play every minute, to experiment and to get himself to the next stage of his career," said the Spaniard, who has now overseen five wins in six league outings.
"You can understand with the options Chelsea have they can allow Romelu to go to an environment for 10 months where he can really benefit. Chelsea get a player who can hopefully fulfil the potential we all know he has.
"He is benefiting from it and the Everton fans are loving every single second of seeing Romelu playing with energy, focus and quality.
"He's enjoying his football and enjoying the way he is fitting into the squad."
Asked how much Lukaku could still improve, Martinez set no upper limit.
"He is getting stronger and stronger and today he was a threat throughout and lasted 90 minutes," he said. "In many aspects he is getting better and stronger.
"He's as good as he wants to be and that's the truth. He's powerful, strong, good in the air, his link up play is impressive, so is his awareness and the positions he picks."
That the game was still goalless when Lukaku struck was hard to believe.
The home side should probably have killed the game inside half an hour.
Benteke saw a powerful penalty well saved by Tim Howard in the seventh minute and the American denied him again with a well-hit effort across goal.
Andreas Weimann somehow contrived to botch a straightforward one-on-one with the goalkeeper moments later and Everton went on to have great chances of their own, Ross Barkley hitting the crossbar with a deflected effort.
Villa boss Paul Lambert declined to attack his side for their early wastefulness, despite the result meaning they have taken just three points from a possible 15 on home turf.
The glut of early opportunities did not escape the Scot though.
"I think we have got to take our chances," he said.
"We should have been three up. But I can't be too harsh on the lads.
"The penalty was a terrific save, I've just seen it again, and the second chance Christian did the right thing in going across the keeper. He just made another great save.
"They're big moments if you don't score.
"Their goalkeeper had a really good game but you don't score when you're well on top and we got caught."
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