Charlton made it a nightmare return to The Valley for Alan Curbishley as counterpart Alan Pardew plunged former club West Ham deeper into trouble.
Darren Ambrose jumps for joy after putting Charlton ahead
West Ham were humiliated as they went three goals down by half-time.
Darren Ambrose put Charlton ahead after 24 minutes and Jerome Thomas slid in a neat second 10 minutes later.
Darren Bent raced clear to add the third five minutes before half-time and Thomas completed West Ham's misery with a crisp strike 10 minutes from time.
It lifted Charlton above West Ham and increased the pressure on Curbishley.
Curbishley received warm applause from Charlton's fans before kick-off after his 15-year reign at The Valley - but it proved to be the high point of his afternoon.
The signs were ominous for West Ham before kick-off, with Charlton able to recall top scorer Darren Bent and England defender Luke Young.
Hammers boss Curbishley, in contrast, lost Luis Boa Morte through illness, and was already without recent captures Lucas Neill and Matthew Upson because of injury.
Curbishley's worst fears were confirmed by a harrowing first 45 minutes that left his team shell-shocked.
Charlton showed all the early intent and it was no surprise when they took the lead.
West Ham appealed for offside as Marcus Bent escaped down the right flank but it was all to no avail as Ambrose arrived at the far post to steer in a side-foot finish.
Darren Bent's pace was exposing the glaring lack of quality and resilience in West Ham's defence but he was wasteful when his cross evaded several players as Charlton launched a swift counter-attack.
There was no escape after 34 minutes when Thomas raced into the penalty area, with defender Calum Davenport simply standing and admiring his handiwork, until he was able to fire into the net across keeper Robert Green.
Nigel Quashie tested Scott Carson with a 25-yard drive but normal service was swiftly resumed as Charlton made it 3-0 four minutes before the interval.
Jimmy Floyd Hasselbaink, on for the injured Marcus Bent, played in Darren Bent, who ran on and buried a comprehensive finish, with West Ham's defence trailing in his wake.
It was the signal for West Ham to deliver a series of uncomplimentary chants towards their bedraggled team - and no-one could blame them after the torture they had suffered in an abject first half.
Curbishley sent on Marlon Harewood for Matthew Etherington for the second half but it was Charlton who almost made it four when Hasselbaink struck the post from 25 yards.
Carlos Tevez's industry and imagination provided a rare glimpse of hope for West Ham but he saw a well-struck free-kick, which was turned over the top by Carson.
The visitors at least showed belated signs of life after half-time, with Carson needing to be alert to save from Davenport and plunge at Harewood's feet.
But any lingering hopes of respectability for desperate West Ham were removed after 80 minutes when Thomas somehow escaped the attention of five defenders in the penalty area to meet Ambrose's cross and beat Green in style.
Charlton almost made it five in the final attack of the game, China international Zheng Zhi heading against the bar.
Charlton manager Alan Pardew:
"The performance was good but today the win was all-important no matter how it came.
"We've set our standards for the rest of the season with this win.
"It's been a difficult day, a difficult week leading up to it for me because I have a genuine love for West Ham and their fans which will never die."
West Ham manager Alan Curbishley:
"I'm as devastated as the fans are. We just can't get any lift-off. We created a bit more second half but the game was over by then.
"We were disappointed about the first goal although it was well finished and we could never come back from it.
"The question is are we going down with a fight or a whimper. There are 10 games left, lots of points at stake."
Charlton: Carson, Young, El Karkouri, Diawara, Thatcher, Ambrose, Holland, Song Billong (Faye 85), Thomas, Marcus Bent (Hasselbaink 35), Darren Bent (Zheng 82).
Subs Not Used: Randolph, Rommedahl.
Booked: El Karkouri, Song Billong, Diawara.
Goals: Ambrose 24, Thomas 34, Darren Bent 41, Thomas 80.
West Ham: Green, Dailly, Ferdinand, Davenport, Konchesky, Benayoun, Mullins (Newton 72), Quashie, Etherington (Harewood 46), Tevez, Cole (Blanco 59).
Subs Not Used: Walker, Pantsil.
Booked: Konchesky, Quashie.
Ref: R Styles (Hampshire).