Hopkins turned it on in the 12th round and punished Ornelas (29-6) over the final 10 seconds. Had he started earlier in the round, Hopkins (50-5-1, 32 KOs) might have won by knockout.
The three judges scored the fight 118-110, 120-108 and 119-109 in favor of Hopkins. The Philadelphia native had a strong crowd at Temple University's Liacouras Center on its feet and proved he's still got some fights left, even at 44.
His next bout, however, might not be a long-awaited rematch with Roy Jones Jr. The two had hoped to fight in March, but Jones was stopped by Australian Danny Green in the first round on Wednesday.
"I think I can still fight him," Hopkins said.
Nearly 14 months after his last bout, Hopkins planned on beating Ornelas in the first step of a three-fight plan to achieve one final championship.
He wanted to fight Jones, then challenge WBA heavyweight champion David Haye.
"I'm now going to be heavyweight champion in 2010," Hopkins said.
If that heavyweight showdown somehow happens, it wouldn't be until late next year.
Hopkins, who once had a perfect 10-year reign as middleweight champion, had the crowd on his side from the moment he stepped through the curtain and was introduced as "the pride and joy of Philadelphia, Pennsylvania."
Eagles quarterback Michael Vick had a ringside seat and Flyers goalie Ray Emery, who has Philly fighters Hopkins, Joe Frazier and fictional Rocky Balboa painted on his helmet, were among the 6,662 fans cheering on Hopkins.
Hopkins dominated Ornelas in the middle rounds and was never in any serious trouble. Hopkins staggered Ornelas with a right to the chin in the fifth and pummeled him with blows to the head in the sixth.
Ornelas, his face swollen by the end, was pounded in the waning moments of the 12th. The bell saved him from further blows.
"I was here for the challenge," Ornelas said. "I'll fight anyone who gives me a chance. I know I don't have the biggest name, but I think I proved something tonight."
Hopkins, known as "The Executioner," was proud of his effort after the lengthy layoff.
"That was great after 14 months. I don't think I looked so bad," he said. "Didn't I look like the same fighter as I always have, even though I'm 44 years old?"
In Sydney, Green floored Jones with a right hand to the head after one minute. Green moved in to apply more pressure and, following a series of blows, English referee Howard Foster stopped the bout after just 122 seconds.
It all but dashed hopes of the next Hopkins-Jones bout. On May 22, 1993, Hopkins lost a unanimous decision to Jones for the vacant IBF middleweight crown.
Hopkins was still eager about promoting a rematch to avenge one of the few defeats of his career.
"I think they stopped the fight prematurely," he said. "That's the whole thing when you go to (Australia). He went out on his feet, not on his back."
