Dirk Kuyt and Peter Crouch scored the goals for Liverpool at Upton Park as West Ham failed to find the spark to breathe life into their Barclays Premiership relegation battle.
Kuyt stunned the hosts with a spectacular strike 12 seconds into the second half and Crouch then celebrated his 26th birthday by finding the top corner and sealing the points.
Kepa Blanco, on loan from Sevilla, came off the bench and scored two minutes into his debut to offer hope but Liverpool held on for their third away win in a row, leaving West Ham still in the bottom three.
Hammers fans could take some comfort from the hosts battling their way through the first half - led by under-fire skipper Nigel Reo-Coker - but there were cries of "we want our money back" before Blanco's strike.
It was a repeat of the FA Cup final nearly nine months ago and little had gone right for West Ham since, not least the form of Reo-Coker.
The England Under-21 midfielder had been criticised for his slump but set the tone early on with a crunching challenge on Steven Gerrard, the hero of Cardiff last May.
Reo-Coker was one of only three players in the starting XI who were in the side for the famous final, and Liverpool fans did not waste an opportunity to remind the Hammers how they let their lead slip in last season's showpiece.
Liverpool, playing three strikers and three centre-backs, were threatening early on despite not appearing to be anywhere near their top gear.
Crouch had an early sight on goal but George McCartney was back to block, while Jamie Carragher fired over when he was left unmarked to receive a free-kick on the edge of the area.
They also thought they should have had a penalty in the 13th minute when a delicious ball from Xabi Alonso found John Arne Riise in the penalty area. The Norwegian went over a challenge by Jonathan Spector but referee Martin Atkinson played on despite the protests.
Hammers goalkeeper Roy Carroll, who had been at fault for Watford's winner at the weekend in their FA Cup tie, looked suspect with his kicking but Liverpool failed to take advantage.
He finally got one right late in the first half and punched the air in delight.
Carroll was exposed when Crouch and Craig Bellamy combined down the right to set up a chance for Gerrard, but the skipper's effort was deflected for a corner.
Reo-Coker had West Ham's first effort, a tame shot after 33 minutes which drew ironic cheers from the home fans, but Marlon Harewood was much closer a minute when his 25-yard effort flew just wide.
Goalkeeper Jose Reina then had to tip over a Luis Boa Morte free-kick eight minutes before the break as the hosts built some momentum, and it no longer looked like third-bottom versus third-top anymore.
The crowd were entertained by Bonnie Tyler singing Total Eclipse of the Heart at the interval and the lyrics "every now and then I fall apart" could not have been more fitting as West Ham were undone just 12 seconds after the restart.
The ball was hit long to Crouch from the kick-off, who laid it back for Kuyt to strike from 25 yards off the underside of the bar. It was his 10th goal of the season.
Crouch doubled the lead in the 53rd minute with a crisp strike into the top corner after Riise had pulled back from the left, capping a slick move from the visitors.
Bellamy could have extended the lead but fizzed an effort just wide, then only Calum Davenport's late intervention prevented the Wales striker opening his account.
The confusion in the hosts' defence was underlined by striker Carlton Cole getting in the way of Carroll when the goalkeeper could have easily claimed a Gerrard free-kick.
Carroll had to be at his best to prevent further embarrassment, saving at his near post from Bellamy and Kuyt.
Blanco was brought on for his debut with 15 minutes remaining and pulled a goal back within two minutes when he slid in to meet Bobby Zamora's cross, but Liverpool held on for the points.
Teams:
West Ham Carroll, Spector, Dailly, Davenport, McCartney,Benayoun, Reo-Coker, Quashie, Boa Morte, Cole (Zamora 73),Harewood (Kepa 76).
Subs Not Used: Green, Pantsil, Mullins.
Booked: Reo-Coker.
Goals: Kepa 77.
Liverpool Reina, Finnan, Hyypia, Agger, Carragher,Bellamy (Gonzalez 85), Gerrard, Alonso, Riise,Kuyt (Fowler 90), Crouch (Pennant 71).
Subs Not Used: Dudek, Zenden.
Booked: Alonso.
Goals: Kuyt 46, Crouch 53.
Att: 34,966
Ref: M Atkinson (W Yorkshire).