كتب : Ahmad Saied
Garcia arrowed the ball into the side netting on the rebound three minutes from time after Arsenal keeper Jens Lehmann parried Steven Gerrard's initial effort.
The victory raised Liverpool's point tally to 51, three behind Manchester United and 15 adrift of leaders and title holders Chelsea.
Below-par Arsenal, who were handed their ninth defeat of the season, remained fifth on 41 points trailing fourth-place Tottenham Hotspurs with four points.
The home side were awarded a controversial spot-kick in the first-half when Fernando Morientes fell down into the area after a challenge by Arsenal right-back Emmanuel Eboue.
Liverpool captain Gerrard stepped up to deliver a low penalty that Lehmann managed to palm away.