Goals from Winston Reid, Diafra Sakho and Morgan Amalfitano boosted the Hammers as Brendan Rodgers' side slumped to another loss seven days after Aston Villa triumphed at Anfield.
Winston Reid and Diafra Sakho capitalized on some poor defending to give the host a surprise lead just seven minutes into Saturday's game at Upton Park.
And, although Raheem Sterling provided hope for the visitors with a 26th-minute finish, West Ham defended admirably to secure all three points, with substitute Morgan Amalfitano making the game safe late.
The Frenchman guided the ball into the far corner with two minutes left to score his first goal since joining West Ham from Marseille in the offseason.
The result marked the Londoners' first home Premier League win of the campaign, while Liverpool's early title ambitions were once again exposed following their defeat at home to Aston Villa in its last Premier League outing.
West Ham boss Sam Allardyce made just one change from the side that drew 2-2 with Hull, handing a full debut to former Barcelona midfielder Alex Song in the center of the park.
Liverpool boss Brendan Rodgers, meanwhile, made three alterations from the midweek UEFA Champions League win over Ludogorets, with Martin Skrtel, Lucas Leiva and Fabio Borini all coming in.
Rodgers once again named three offseason signings — Alberto Moreno, Dejan Lovren and Javier Manquillo — to his back line, but that trio could not prevent the visitors from making a shambolic start in defense.
With just two minutes gone, a West Ham set piece caused chaos in the area and allowed James Tomkins to nod the ball back into the middle, where Reid was on hand unmarked to bundle an effort home.
It went from bad to worse for Liverpool a few moments later, as Sakho's chip from the right found the far corner of the net, with goalkeeper Simon Mignolet flailing.
Rodgers had clearly seen enough and soon withdrew Manquillo for Mamadou Sakho in order to switch to a 3-5-2 formation more suited to negating West Ham's threat in the air.
But it was at the other end of the pitch that Liverpool was given brief hope of a turnaround.
Mario Balotelli produced a fine piece of control in the box after 26 minutes before getting a shot off that was well blocked, but Sterling was on hand to smash home the rebound.
West Ham continued to threaten despite that goal and soon caused more disarray in the Liverpool defense that led to Lovren and Sakho clashing heads in the air.
The Croatian appeared to come off worst but he managed to continue after a spell of treatment.
Perhaps unsurprisingly, Liverpool made a further change after hanging on until the break as Adam Lallana replaced the ineffective Lucas.
And the 25 million pound man's introduction almost paid immediate dividends as he set up Sterling for a shot from the edge of the box that trickled wide.
Lallana proved to be a catalyst for an improvement in Liverpool's previously ragged attacking play, although West Ham remained a real threat on the counterattack.
The England international set up Borini to drive a shot just wide before, at the other end, the hosts broke at pace and Sakho chipped onto the roof of the net.
Rodgers threw on Rickie Lambert 15 minutes from time in an attempt to find an equalizer, but West Ham killed the game off when Amalfitano toe-poked home at the end of a flowing move.