"I want to thank my mom for the left hand. My whole family's lefthanded, and that's what I got him with," Garcia said after the fight.
Garcia set up his winning knockout with a pair of right jabs.
On Thursday, Golden Boy Promotions confirmed that Morales had tested positive for a banned substance. Morales failed a pair of tests before passing his third on Friday morning. According to Golden Boy CEO Richard Schaffer, Morales tested positive for Clenbuterol, a weight-loss aid. He failed to make weight for his March fight with Garcia and vacated his WBC belt before the bout.
"We knew Morales was a little suspicious with the anti-doping," said Danny Garcia's father and trainer, Angel Garcia. "I'm not calling him a dopey, but his urine was bad, but we still went along with it."
Angel Garcia said he was ready to pull out of the fight as there's no amount of money that can equal his son's life. Danny Garcia's purse for the fight totaled $1 million. But, on Saturday morning Danny Garcia said his mother, Marissa Garcia, had a gut feeling her son would win which prompted him to go on with the bout.
Early in the fight, Garcia noticed that his jab was effective enough to back Morales up, which created ample room for his hook.
"I just stood in the pocket, turned my whole body and hit him perfectly with the left hook," said Garcia. "And he just landed."
In the third round, Garcia backed Morales into the ropes with a strong right hand, but before he could inflict any more damage the bell rang. A confused Morales went to the wrong corner before being redirected to his own.
Garcia controlled the fight by using his left hook at will. In the second round, he backed up Morales against the ropes before badgering him with body shots. He then threw a menacing hook that whiffed. Garcia kept Morales off balance as his hook was just as effective on the body as it was on the head.
In the first round, Garcia displayed his quickness, as he eluded a strong right hook from Morales. In the middle of the round, the New York crowd showed their favoritism for Garcia chanting, "Danny! Danny!"
Philadelphia boxing legend Bernard Hopkins sat at ringside as did former heavyweight champion Mike Tyson.
On the undercard, Brooklyn's own Paulie Malignaggi pulled out a split-decision win over Pablo Caesar Cano to retain his WBA world welterweight title. Malignaggi opened a large cut above Cano's right eye in the second round but wasn't able to target it as much as he liked.
Cano wisely fought with his gloves in front of his face and absorbed Malignaggi's strong jabs. Cano sent Malignaggi to the mat in the 11th round and had him staggered as the round ended.
"I don't know what the one scorecard was all about," Cano said. "I was in control of the whole fight."
West Philadelphia welterweight Steve Upsher Chambers dropped an eight-round unanimous decision to Luis Collazo. It was Chamber's first loss since May 2004.
With the hometown crowd behind him, New York's Peter "Kid Chocolate" Quillin displayed a strong right hand to knock down Hassan N'Dam twice in the fourth round en route to a unanimous decision to capture the WBO middleweight title.
Randall Bailey lost his IBF welterweight title with a unanimous decision to Devon Alexander. It was Bailey's first title defense since knocking out Mt. Airy's Mike Jones.
Contact Matt Breen at firstname.lastname@example.org or @matt_breen on Twitter.