The 10th seed, who was troubled by a side strain in the run-up to the Grand Slam, was broken five times in the match on Centre Court by her French opponent, ranked 55 in the world.
Raducanu, 19, was on the back foot early in the contest after being broken in her first service game and won just 45 percent of points on her first serve.
Garcia, fresh from winning on grass at Bad Homberg, hit 25 winners in an impressive display.
“Emma is a huge player and in her home tournament and she proved she can do very well on the big stage,” said Garcia.
“I really enjoyed playing on Centre Court, it was my first time and very special.”
Raducanu has struggled with a string of minor injuries since her sensational win at Flushing Meadows last year.
She has also come under scrutiny over her failure to settle on a long-term coach.