SHANE Long's seventh Barclays Premier League goal of the season proved nothing more than a consolation as Albion suffered their joint-worst home defeat of the campaign.
The half-time substitute gave the Baggies hope of another grandstand finish against the Toon with a 53rd minute strike to make it 3-1.
But, unlike last term's Somen Tchoyi hat-tick-inspired St James' Park draw, Roy Hodgson's men were unable to cancel out United's three-goal lead on this occasion.
Papiss Cisse's double - netting in the sixth and 34th minutes - and&nbsp;Hatem Ben Arfa's 12th-minute effort collected all the points for Alan Pardew's sixth-placed outfit, as Albion remained 14th in the table and 11 points clear of the drop-zone.
Hodgson made four changes to his side, with Nicky Shorey, Chris Brunt, Paul Scharner and&nbsp;Long all dropping to the bench. Jonas Olsson, back from suspension, and fit-again Peter Odemwingie (calf) were restored to the starting XI along with Keith Andrews and Marc-Antoine Fortune.
And inspired by a minute's applause just before kick-off in honour of club legend Ray Barlow, who sadly died aged 85 earlier this month, Albion came flying out of the blocks.
Jerome Thomas presented Youssouf Mulumbu with a chance to shoot in the opening minute - but the former PSG midfielder could not find the target as his 20-yard shot rose over the bar.
Ben Foster was called into action in the fifth minute as Demba Ba pounced on Liam Ridgewell's headed clearance and forced the Baggies keeper to tip the ball over after drilling his effort into the turf from the edge of the box.
Just a minute later, the visitors snatched the lead when Ben Arfa raced onto Jonas Gutierrez's pass and squared for Cisse to tap home from close range.
Things went from bad to worse for Albion as a swift United break from their own box saw Ridgewell unable to stop Ben Arfa on the halfway line before the Frenchman exchanged passes with Cisse and kept his cool, under pressure from Olsson, to fire home just inside the far post from 15 yards.
The shell-shocked Baggies looked to get a foothold in the game and, on 18, James Morrison swivelled on Gareth McAuley's chest down and sent an 18-yard first-time volley a fraction past the left-hand angle of post and bar.
A neat exchange of passes between Morrison, Thomas and Ridgewell in the 22nd minute saw the latter deliver a left-wing centre that Gutierrez just beat Fortune to.
The ball remained in play and Billy Jones produced another cross from the opposite flank that Fortune could not stretch high enough to direct on target at the back post.
Five minutes later, the ex-Celtic hitman teed up Andrews, whose goalbound strike from the edge of the area was blocked.
Thomas picked up the loose ball and found Ridgewell, who saw his cross planted just over the bar from Fortune's meaty 15-yard header.
Odemwingie had the ball in the back of the net in the 32nd minute after good work by Fortune - but the Nigeria&nbsp;international's tap-in was ruled out after Fortune was adjudged to be&nbsp;off-side.
Just when it looked like Albion might find a way back into the game, they were undone by a sucker punch on the counter-attack.
Ba back-heeled the ball to Ben Arfa and he cut it back from the left-hand byline for Cisse to stroke home his second of the game and give the Magpies a three-goal lead on 34.
Hodgson made a double change at the break as he switched to a 4-4-2 formation, with Brunt coming on for&nbsp;Thomas on the left and Long for Andrews to make the extra striker.
Odemwingie and Fortune also swapped positions, while United made a change at the back, with Davide Santon coming on for Fabricio Coloccini.
Mulumbu came close to levelling four minutes after the restart but was unfortunate to see his goalbound strike deflected inches wide by Williamson's outstretched leg.
Disaster almost struck for the hosts a minute later when Cabaye played Cisse clean through and only a superb save by Foster denied the Senegal international his hat-trick.
Odemwingie put pressure on Williamson from a long punt up field on 53 and the Newcastle defender got in a mess with Tim Krul.
Long pounced on the loose ball&nbsp;to fire into the empty net from 12 yards and give the Baggies a lifeline.
A minute later, Krul was forced to beat out Odemwingie's fiercely-struck shot at his near post.
But at the other end, the Baggies found themselves stretched by Ben Arfa again and he forced Foster into another fine save low to his left, with Olsson mopping up the rebound.
The hosts continued to press and, on 63, Mulumbu was quickest to react on the edge of the box and he was again unlucky to see his left-foot strike blocked by Williamson.
Hodgson was forced into a change in the 74th minute as Mulumbu limped off to be replaced by Scharner.
Having used all their subs, Albion found themselves down to ten men eight minutes from time as Morrison was helped off the field having done damage to his left leg.
Even a man down, the Baggies refused to give up hope and United twice needed blocks in the box to deny Ridgewell and Brunt before the game moved into seven minutes of stoppage time.
James Perch had to be alert in the 94th minute to nick the ball off Long's head inside the box from Ridgewell's diagonal ball -&nbsp;but there was no way United were going to throw away a precious three points in their quest for European football.
ALBION (4-5-1): Foster; Jones, McAuley, Olsson, Ridgewell; Odemwingie, Mulumbu (Scharner 74), Morrison, Andrews (Long HT), Thomas (Brunt HT); Fortune. Subs not used: Daniels (gk), Cox, Dawson, Shorey.
NEWCASTLE (4-4-2): Krul; Simpson, Coloccini (Santon HT), Williamson, Perch; Ben Arfa (Shola Ameobi 75), Guthrie, Cabaye, Gutierrez; Ba, Cisse (Ferguson 79). Subs not used: Elliot (gk), Abeid, Gosling, Vuckic.
GOALS: ALBION - Long (53). UNITED - Cisse (6, 34), Ben Arfa (12).
BOOKINGS: UNITED - Williamson (foul 69). REFEREE: C Foy (Merseyside).
ALBION STARMAN: Ben Foster.