ROBIN van Persie's 29th goal in only 28 Barclays Premier League games in 2011 set Albion on their way to a second successive defeat.
The Gunners skipper opened the scoring in the 22nd minute and Thomas Vermaelen doubled the lead six minutes before the break, putting heavy Arsenal gloss on a first half in which the Baggies had largely matched their illustrious hosts.
Roy Hodgson's men battled to regain a foothold in the match after the break but the game was up on 74 when Mikel Arteta struck a fine third past the helpless Ben Foster.
Seventh entertained 13th as the Baggies took on a resurgent Arsenal side who had won five games on the bounce before their goalless Champions League draw with Marseille in midweek.
Shortly before kick-off, you couldn't hear a pin drop inside the Emirates Stadium as players, supporters and officials alike observed a minute's silence ahead of Armistice Day on Friday.
Zoltan Gera was handed his long-awaited second Albion debut as Hodgson made four changes. Simon Cox, making his first Barclays Premier League start of the campaign, James Morrison and Graham Dorrans also came in, with injured duo Peter Odemwingie and Paul Scharner, plus benched pair Somen Tchoyi and Youssouf Mulumbu, making way.
Arsenal predictably made the early running but Albion defended resolutely and they limited the hosts to a long-range, not to mention, wayward Andre Santos free-kick in the opening ten minutes.
There were worrying signs for Albion in the 13th minute, though, when Jonas Olsson suffered a nasty, albeit accidental, blow to the head as he contested a van Persie free-kick with Vermaelen. It took a couple of minutes for the club's medical staff to clean up a nasty gash on the Swede's left cheek and the Baggies had to play on with ten men until he was able to return to the field in the 18th minute, having had to change his blood-stained shirt AND shorts.
Albion had settled into this game very nicely and, a minute later, a flowing move sparked by Steven Reid and Chris Brunt forced Wojciech Szczesny into taking evasive action at his near post to cut out a Cox centre, thus denying Gera a simple tap-in.
But Arsenal took the lead on 22 with a goal that came completely out of the blue.
There looked little danger when Aaron Ramsey took the ball midway inside the Baggies half but he dissected the visitors' backline with an inch-perfect pass to Theo Walcott.
The winger cut into the box and was brilliantly denied by one-time England team-mate Ben Foster, only for the rebound to fall into van Persie's path and he tapped into an empty net.
There had been little between the two teams before Arsenal's goal and that is how the pattern of the game continued until a major talking point arrived in the 36th minute.
The lively Morrison surged at the Gunners' defence before clipping a ball across the penalty area and finding Jerome Thomas. The ex-Arsenal winger appeared to be barged off the ball by Laurent Koscielny as he shaped to shoot - but referee Michael Oliver waved his penalty protests away.
That incident took on even greater significance three minutes later when Arsenal doubled their lead.
Alex Song picked out van Persie at the back stick with a diagonal ball and the Dutchman lashed it back into the danger-zone, enabling Vermaelen to ghost forward and beat Foster all ends up with a first-time drive from 15 yards.
Six minutes later, Oliver's whistle brought to an end a half in which Albion had enjoyed plenty of possession and restricted Arsenal chances - but somehow found themselves 2-0 down.
Albion threatened first after the restart and following more good build-up play, Dorrans failed to trouble the Arsenal goal with a tame 20-yard effort which dribbled wide of the right-hand post.
At the other end, Gareth McAuley denied Gervinho an easy chance with a vital near-post interception from Carl Jenkinson's cross. Albion had a real reprieve from van Persie's ensuing corner, with the woefully unmarked Vermaelen heading wide from eight yards.
The Baggies were posing more of a goal threat after the break and Morrison did brilliantly to set up another shooting chance for Dorrans, who again shot wide from the edge of the box.
Moments later, Billy Jones floated a free-kick into the Arsenal box and from McAuley's header, Brunt saw an audacious scissor kick sail high over the bar.
Back came Arsenal and Ramsey flashed a terrific effort across the face of goal following good Gervinho approach play.
McAuley came to Albion's rescue again on 64 when he diverted Jenkinson's cross away from goal with two Arsenal players ready to pounce.
Arsenal were now getting on top and Foster did well to keep out Gervinho's acute drive.
Albion had a half-chance themselves on 67 when Santos made a hash of dealing with Olsson's ball and gifted Brunt possession in the box, but the captain was unable to find unmarked sub Tchoyi and Koscielny cleared.
The Gunners broke upfield and Foster had to produce a superb save to keep out Song's stinging 15-yard shot from Gervinho's pass.
But it was game over on 74 as Arsenal made it 3-0.
A move that was spearheaded by van Persie culminated in sub Tomas Rosicky squaring to Arteta who gave Foster no chance with a 16-yard effort that nestled just inside the left-hand post.
Albion's best chance of the game came in the 80th minute when Morrison dissected the Arsenal rearguard with a sublime through-ball to put Tchoyi clear. However, the Cameroon forward delayed getting his shot away, enabling the recovering Vermaelen to block his goalbound drive.
In the 86th minute, Szczesny had to make a fine save low to his left to keep out Reid's downward header from a Brunt corner.
To their credit, Albion kept going until the death and, two minutes later, Morrison stung Szczesny's hands with a 15-yard drive from sub Mulumbu's lay-off.
ARSENAL (4-4-2): Szczesny; Jenkinson, Vermaelen, Koscielny, Santos; Walcott (Arshavin 78), Ramsey (Rosicky 71), Song, Arteta; Gervinho (Benayoun 71), van Persie (c). Subs not used: Fabianski (gk), Mertesacker, Park, Djourou.
ALBION (4-4-1-1): Foster; Reid, McAuley, Olsson, Jones; Brunt (c), Dorrans (Thorne 80), Morrison, Thomas; Gera (Tchoyi 63); Cox (Mulumbu 71). Subs not used: Fulop (gk), Shorey, Dawson, Fortune.
GOALS: ARSENAL - van Persie (22), Vermaelen (39), Arteta (74).
REFEREE: M Oliver (Northumberland).
ALBION STARMAN: James Morrison.