The 30-year-old Garcia retained his WBC title and grabbed Easter's IBF belt with a unanimous decision victory at Staples Center arena in downtown Los Angeles, AFP reported.
"It is a great accomplishment. Now we are back," said Garcia.
"I prepared for the best. He gave a great fight but I was in control most of the fight and did what I had to do to win."
Garcia seized control of the fight early, flooring American Easter in the third round with a left hook to the chin. It was just the second time in his career that Easter was knocked down.
"We wanted to land that right hand. It was a perfect punch around the chin," he said.
Easter recovered from the knockdown but failed to mount a sustained attack outside of using his jab, and was almost knocked down again in the ninth round.
Garcia is now 5-0 with two knockouts since returning from a 30-month exile from the sport due a battle with promoter Top Rank.
The three judges scored it 118-109, 117-110 and 116-111 as Garcia improved to 39-0 overall after this fight, which marks a return to the lightweight division. He won a junior welterweight belt in February but had to vacate it to face Easter.
Garcia immediately threw down the gauntlet to Errol Spence saying in the ring that for his next fight he wants to move up to the welterweight division to fight for Spence's IBF belt.
"He is the most feared man and I want to challenge him," said Garcia.
The 27-year-old Easter suffered the first loss of his career to drop to 21-1, with 14 KOs. He was making his fourth title defense of the vacant belt he won in 2016.