Champions League-chasing Newcastle capitalised on poor West Ham defending to hit five goals at London Stadium and pile the pressure on Hammers manager David Moyes.
Callum Wilson and Joelinton put the visitors two ahead inside 15 minutes, before Kurt Zouma pulled one back.
But blunders by Nayef Aguerd and Lukasz Fabianski allowed Wilson to double his tally and Alexander Isak to add a fourth, with Joelinton making it five in stoppage time.
Defeat leaves West Ham outside of the relegation zone on goal difference.
Moyes' side are one of four teams on 27 points, alongside Everton, Nottingham Forest and 18th-place Bournemouth.
Newcastle remain third and are now three points clear of fifth-placed Tottenham with a game in hand, following a fourth successive win for Eddie Howe's side.
Hapless Hammers taken apart
While there have been a remarkable 13 managerial changes in the Premier League this season, Moyes has managed to remain in the West Ham dugout - however the Hammers' abysmal defending here has made his position even more tenuous.
After starting well - a low cross from Jarrod Bowen forcing Bruno Guimaraes to turn the ball onto his own post inside the first minute - the hosts were responsible for their own downfall.
For the opener, Thilo Kehrer headed a deep cross behind under no pressure. The resulting corner was half-cleared and Allan Saint-Maximin's cross found Wilson unmarked 12 yards out to head in - and the lapses steadily got worse for the home defence.
The second saw a single Fabian Schar long ball beat the whole backline, with Zouma failing to track the run of Joelinton while Emerson did not step up with his fellow defenders to play the Brazilian offside.
Joelinton rounded Fabianski to score and though the goal was initially flagged offside it was allowed following a VAR check.
West Ham briefly woke up and pulled one back when Nick Pope was caught under a Bowen corner, allowing Zouma to powerfully head in and give some hope to the home fans.
But seconds into the second half Aguerd dawdled on a rolled ball from Fabianski, allowing Jacob Murphy to steal the ball and square for a Wilson tap-in.
The defensive shambles coup de grace was saved for the fourth as the Polish keeper rushed out of his goal and miscontrolled a long ball, allowing Isak to lob into an empty net.
By the final whistle London Stadium was half-empty, with Moyes left looking nervously over his shoulder.
Newcastle stay on top-four course
Wilson must love playing against West Ham - not only has he now scored 12 in his last 13 games against the Londoners, he continues to get one over on his podcast co-host.
On the Footballers' Football Podcast, Wilson promised Michail Antonio he would do the Macarena in celebration should he score - and he was as good as his word for the opener.
Newcastle are often dancing after they face West Ham - this was their 11th away Premier League win over the Hammers, their joint-most against a single team in the division alongside Spurs.
This was a fourth straight league win for Howe's side - the second time this season they have gone on such a run - and one which puts them firmly in the Champions League qualification driving seat.
They did have to dig deep in the first half, Pope making a good save from a Lucas Paqueta free-kick shortly before a superb last-ditch tackle by Sven Botman denied Antonio.
But West Ham's farcical defending made the second 45 minutes much more comfortable for Newcastle, rounded off by Joelinton sprinting clear of the defence and firing low into the bottom corner past Fabianski.
Line-ups
West Ham
Formation 4-2-3-1
1Fabianski
24Kehrer4Zouma27Aguerd33Emerson
28Soucek41Rice
20Bowen11Lucas Paquetá22Benrahma
9Antonio
1Fabianski24KehrerSubstituted forCoufalat 63'minutes4Zouma27Aguerd33EmersonBooked at 42mins28SoucekSubstituted forDownesat 63'minutesBooked at 88mins41Rice20Bowen11Lucas Paquetá22BenrahmaSubstituted forCornetat 63'minutes9AntonioSubstituted forIngsat 63'minutesSubstitutes
3Cresswell5Coufal8Fornals10Lanzini12Downes13Aréola14Cornet18Ings21OgbonnaNewcastle
Formation 4-3-3
22Pope
2Trippier5Schär4Botman33Burn
36S Longstaff39Bruno Guimarães7Joelinton
23Murphy9Wilson10Saint-Maximin
22Pope2TrippierSubstituted forManquilloat 87'minutes5Schär4Botman33BurnSubstituted forTargettat 85'minutes36S Longstaff39Bruno Guimarães7JoelintonBooked at 52mins23MurphySubstituted forWillockat 64'minutes9WilsonSubstituted forIsakat 64'minutes10Saint-MaximinSubstituted forGordonat 64'minutesSubstitutes
1Dúbravka6Lascelles8Gordon11Ritchie13Targett14Isak19Manquillo28Willock32AndersonLive Text
Match ends, West Ham United 1, Newcastle United 5.
Second Half ends, West Ham United 1, Newcastle United 5.
Goal! West Ham United 1, Newcastle United 5. Joelinton (Newcastle United) left footed shot from the centre of the box to the bottom right corner. Assisted by Bruno Guimarães following a fast break.
Attempt blocked. Anthony Gordon (Newcastle United) right footed shot from the right side of the box is blocked. Assisted by Joe Willock.
Flynn Downes (West Ham United) is shown the yellow card for a bad foul.
Joe Willock (Newcastle United) wins a free kick in the defensive half.
Foul by Flynn Downes (West Ham United).
Substitution, Newcastle United. Javier Manquillo replaces Kieran Trippier.
Substitution, Newcastle United. Matt Targett replaces Dan Burn.
Goal! West Ham United 1, Newcastle United 4. Alexander Isak (Newcastle United) right footed shot from outside the box to the top right corner.
Foul by Joe Willock (Newcastle United).
Jarrod Bowen (West Ham United) wins a free kick on the right wing.
Corner, West Ham United. Conceded by Dan Burn.
Attempt missed. Bruno Guimarães (Newcastle United) right footed shot from outside the box is close, but misses to the left. Assisted by Joelinton.
Attempt blocked. Joe Willock (Newcastle United) left footed shot from the centre of the box is blocked. Assisted by Anthony Gordon.
Sven Botman (Newcastle United) wins a free kick in the defensive half.
Foul by Kurt Zouma (West Ham United).
Corner, West Ham United. Conceded by Dan Burn.
Attempt blocked. Danny Ings (West Ham United) right footed shot from outside the box is blocked. Assisted by Nayef Aguerd with a headed pass.
Foul by Kieran Trippier (Newcastle United).
Player of the match
IsakAlexander Isak
West Ham United
Squad number41Player nameRice
Squad number20Player nameBowen
Squad number4Player nameZouma
Squad number11Player nameLucas Paquetá
Squad number1Player nameFabianski
Squad number9Player nameAntonio
Squad number27Player nameAguerd
Squad number22Player nameBenrahma
Squad number33Player nameEmerson
Squad number28Player nameSoucek
Squad number14Player nameCornet
Squad number12Player nameDownes
Squad number24Player nameKehrer
Squad number5Player nameCoufal
Squad number18Player nameIngs
Newcastle United
Squad number14Player nameIsak
Squad number9Player nameWilson
Squad number7Player nameJoelinton
Squad number2Player nameTrippier
Squad number10Player nameSaint-Maximin
Squad number28Player nameWillock
Squad number39Player nameBruno Guimarães
Squad number5Player nameSchär
Squad number23Player nameMurphy
Squad number4Player nameBotman
Squad number8Player nameGordon
Squad number19Player nameManquillo
Squad number13Player nameTargett
Squad number33Player nameBurn
Squad number22Player namePope
Squad number36Player nameS Longstaff
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