Garcia caught his opponent with a powerful left hook to send him crashing to the canvas and prompt referee Benji Esteves to stop the bout.
The 24-year-old will now consider whether to offer Amir Khan a rematch following his fourth-round win over the Bolton fighter in July this year.
"I'm glad to have it done early, I thought this fight was going the distance," said Garcia, who improved his record to 25-0.
"He's a crafty veteran. I wanted to set up my power punches and give him a little extra. I get that from my mom, all my family is left-handed."
On his next opponent, Garcia said: "I won't duck anybody. I've got the titles. If you want them, come and get them. But it ain't going to be easy."