Gerrard marked his return from injury with a 23rd minute header which ensured qualification from Group D with one match still remaining.
The Reds are not yet assured of winning the group as they remain locked on points with Atletico Madrid but behind the Spanish side on goal difference ahead of an important round of final fixtures.
But this was hardly a vintage showing from the Merseysiders, who were again indebted to their skipper for providing the decisive moment in a game in which they were second best for long spells.
Gerrard missed last weekend's goalless Premier League draw with Fulham with the same groin injury which forced him out of England duty last week.
But he underlined his importance to the Reds with a well-taken header midway through the first period.
Liverpool had dominated the opening exchanges without creating any real openings, until Dirk Kuyt headed a Fernando Torres cross straight at the keeper.
Steve Mandanda spilled the ball and required a defender to put it behind and it was from the resulting corner that the home side took the lead.
Gerrard's short corner routine resulted in a comfortable headed clearance but, when Xabi Alonso sent back over a deep cross, the influential midfielder found himself totally unmarked as he headed home from eight yards at the back post.
The goal seemed to shake Marseille into life and they ended the first half on a high when a hopeful Taye Taiwo free-kick from 30 yards hit the base of the post with Pepe Reina scrambling to cover the ambitious shot.
Ronald Zubar then headed a corner which Reina flapped at wide from close range as Anfield collectively held its breath.
But nerves really were frayed during a second half in which Liverpool sat back and could count themselves fortunate not to concede in.
First Bakary Kone took a swipe at fresh air after Karim Ziani's sensational lofted pass played him in behind the defence.
Mamadou Niang got the better of Jamie Carragher in the 55th minute with a clever shimmy but his shot from 20 yards was straight down the throat of Reina
Marseille should have pulled themselves back on level terms ten minutes later when Hatem Ben Arfa reached the bye-line only to pull the ball back behind Benoit Cheyrou, who would almost certainly have tapped home.
Reina was to have the last word as he tipped a thunderous free-kick from Ben Arfa, which was heading for the top corner, behind for a corner with an acrobatic save.
Liverpool must now defeat PSV Eindhoven in the final group stage match and hope Atletico Madrid slip up in Marseille if they are to win the group and avoid drawing one of Europe's heavyweights in the first knockout round.