SPOT-ON Graham Dorrans fired the brilliant Baggies into the FA Cup fifth round for the third time in four seasons as Roberto Di Matteo's men finally got the better of ten-man Newcastle.
Albion cruised into a 2-0 lead inside 31 minutes when Jonas Olsson made it two goals in as many games against the Toon and Graham Dorrans tucked away a penalty.
The visitors upped their game at the start of the second half and striker Andy Carroll pulled a goal back on 62.
But Coca-Cola Championship leaders Newcastle's fightback was nipped in the bud when full-back Ryan Taylor was dismissed 19 minutes from time for tripping Jerome Thomas in the box.
Ice-cool Dorrans again made no mistake from the spot and Thomas put the tie firmly beyond United's reach five minutes later by making it 4-1.
Carroll's second of the game in the first minute of stoppage time proved nothing more than a consolation.
The resounding victory somewhat made up for the four league points Albion have dropped against Chris Hughton's men this term, having created the better chances in both games.
Di Matteo named an unchanged side from the two teams' last encounter five days ago. The only alteration to his 18 saw fit-again Shelton Martis replace Luke Moore on the bench.
Hughton made five changes as keeper Tim Krul, Ryan Taylor, Fabrice Pancrate, Carroll and Tamas Kadar came in for Steve Harper, Shola Ameobi, Peter Lovenkrands, Steven Taylor and Danny Simpson.
After the club showed their support for the Disasters Emergency Committee's Haiti Earthquake Appeal by adding the DEC's website details to the front of their shirts at St James' Park, a minute's silence was impeccably observed before kick-off in memory of the thousands of victims.
Monday's game proved a cracker - and this one got off to a flyer as both teams spelled out right from the start their intentions to win the tie at the first time of asking.
There had already been plenty of end-to-end action when Gabriel Tamas tested Krul with a fierce 20-yard shot which made its way through a sea of legs after the Toon had only partially cleared Dorrans' corner.
Albion started to get on top and the tireless Roman Bednar fizzed an angled drive just over the bar when he would have been better served crossing to unmarked team-mates following a fine right-wing move
Newcastle's first threat on the Baggies goal arrived on 15 when Carroll rose above the home defence to head wide from Jonas Gutierrez's left-wing centre.
Back came Albion, who were showing bags of invention every time they broke, and Thomas saw an 18-yard drive deflect off a Newcastle defender and fly just wide.
And it was from Chris Brunt's ensuing 17th minute corner that the hosts took the lead.
Olsson ghosted in at the near post to head powerfully goalwards and although Jose Enrique cleared, the referee's assistant, Duncan Street, instantly flagged that the ball had crossed the goalline.
The game suffered a short lull in goalmouth action before fine work between Robert Koren and Thomas set up a half chance for Dorrans, but the Scotland international dragged his shot harmlessly wide from the edge of the box.
Albion extended their lead on 31 - and it was all down to Bednar's never-say-die attitude.
The Czech striker looked second-favourite to reach Brunt's ball over the top but he muscled his way in front of Tamas Kadar, who then pulled him down in the box to concede a penalty.
Dorrans made no mistake from 12 yards, clinically tucking the ball into the right-hand corner.
Albion finished the half on top, although Brunt failed to trouble Krul with two long-range efforts.
The final action of the opening 45 came from a rare United foray into the Baggies half.
Carson first had to be alert to palm away the marauding Enrique's left-wing centre before Danny Guthrie saw his follow-up effort deflected wide by Marek Cech.
Newcastle appeared much more 'up for the cup' when they came out for the second half and Carson had to make his first difficult save of the game on 53 when he pushed away sub Amoebi's 20-yard pile-driver.
But Albion still looked comfortable as they tried to exploit the extra space being left in the Newcastle half by the visitors throwing caution to the wind in a desperate effort to claw a goal back.
However, the Baggies had a huge scare on 58 when Ryan Taylor went down in the box under Dorrans' challenge - but referee James Linington waved away the Toon's loud penalty appeals.
Newcastle did halve the deficit on 62, though.
Gonzalo Jara had been pretty adept at keeping danger-man Gutierrez quiet but that all changed when the Argentinian skipped past the Chilean and centred to Carroll, who smashed a fine volley home from 12 yards.
United were now piling forward with real purpose while Albion were struggling to get out of their own half.
And the visitors had more spot-kick claims turned away on 68 when Olsson, Amoebi and Tamas all went to ground in the box.
Incredibly, Albion surged straight upfield and won their second penalty of the game when Ryan Taylor was penalised for a clear trip on Thomas as he raced onto Koren's sublime throughhball.
Newcastle's cause was made much worse by Taylor being dismissed for the offence, which the referee deemed as denying Thomas a clear goalscoring opportunity.
And Dorrans piled on the Toon's misery by comfortably beating Krul from the spot on 72, planting the ball in the exact same part of the net.
It was definitely game over five minutes later when Enrique, in trying to prevent Bednar getting on the end of Koren's throughball, inadvertently poked it into the path of Thomas who slotted home from six yards.
Incredibly, sub Ishmael Miller would have made it five had he not been denied at point-blank range by Krul after being slotted through by Koren.
Carroll pulled a consolation back by poking home from close range in the first minute of stoppage time.
ALBION (4-5-1): Carson; Jara, Tamas, Olsson, Cech; Brunt (Zuiverloon 67), Dorrans, Mulumbu, Koren, Thomas (Mattock 77); Bednar (Miller 77). Subs not used: Kiely (gk), Martis, Cox, Teixeira.
NEWCASTLE (4-5-1): Krul; R Taylor, Coloccini, Kadar, Enrique; Pancrate (Ameobi HT (Ranger 80)), Nolan, Smith, Guthrie (Donaldson 81), Gutierez; Carroll. Subs not used: Harper (gk), LuaLua, Tozer, Ferguson.
GOALS: ALBION - Olsson (17), Dorrans (31 & 72 both pens), Thomas (77). NEWCASTLE - Carroll (62 & 90+1)).
BOOKINGS: NEWCASTLE - Kadar (foul 30), Krul (ungentlemanly conduct 79), Smith (foul 87), Enrique (foul 90+2).
SENDING OFF: NEWCASTLE - R Taylor (professional foul 71).
REFEREE: J Linington (Isle of Wight).
ALBION STARMAN: Roman Bednar.