Goals by in-form Freddie Ljungberg, in the 77th minute, and Kanu, just three minutes later, put further daylight between the Gunners and the chasing pack and left Hammers cursing the cruel luck that denied them a first half lead.
Who knows how this entertaining London derby would have ended but for the inaction of the assistant referee, who failed to recognise that Fredi Kanoute's 37th minute shot had clearly crossed the goalline BEFORE Ashley Cole scooped the ball clear.
The official may try to argue that his view of the ball was obscured by Cole's outstretched body, but the England left-back's legs were so far beyond the chalk mark to surely confirm the goal. Where was the Russian linesman when we needed him?
It was very hard on Hammers and, in particular, Kanoute who could have had a hat-trick even before his disallowed effort. Glenn Roeder put out a side - playing 5-4-1, with the so-called wingbacks always likely to be defending rather than attacking - to contain and frustrate the rampant Gunners.
The plan was almost killed inside the first three minutes, though, when David James had to be at his sharpest to make two saves from Ljungberg, with Arsenal's midfield threatening to run riot.
But after weathering the initial storm, the visitors regained composure and started to enjoy promising openings on the counter-attack, with Kanoute - the lone striker, now that Jermain Defoe was back on the bench - the focal point.
The Frenchman, recovered from the heavy cold that ruled him out of Saturday's home win over Sunderland in which Defoe again scored, went close with a near-post header from Trevor Sinclair's left wing cross, and then from the same angle following a Joe Cole pass.
Kanoute missed the best chance of the half, though, when he eluded both of Arsenal's ageing central defenders, Tony Adams and Martin Keown, in the 18th minute, but lifted his shot over David Seaman and the crossbar from just eight yards, with the North Bank net gaping.
By then, Roeder was forced to bring on Vladimir Labant on the left of midfield and switch Sinclair to the right after Sebastien Schemmel collapsed near the touchline after what looked an innocuous challenge by Ashley Cole. An X-ray in the Highbury dressing room later revealed a fractured bone in his foot, ruling the Frenchman out for the remaining two games of the season.
The second half was one-way traffic, with Seaman not asked to make a save, as Gunners stepped up another gear. James again showed bravery to dive at the feet of Ray Parlour, then block Henry's follow-up, while Henry and the impressive Dennis Bergkamp both saw shots from distance flash narrowly wide of either upright.
Defoe's arrival from the bench usually signals a goal, but on this occasion it was West Ham who conceded just three minutes after replacing the luckless Kanoute.
Bergkamp, the best player on view, orchestrated the attack from deep and picked out yet another intelligent Ljungberg run. The Swede, escaping his markers, didn't get much of a touch on the ball but it was enough to see it squeeze inside the far corner of the net.
Highbury reverberated to the sound of Arsenal fans in party mood and there was no surprise when, three minutes later, Kanu slipped in unmarked at the far post to volley Ljungberg's cross past James.
It was a sorry end to a nostalgic night for Nigel Winterburn - 12 years a Gunner - who was last off the field to a standing ovation in what is likely to be his final game at the ground he graced for so long.
2 - Ljungberg fires in a rasping low effort from the edge of the box that is tipped round for a corner by James.
4 - With Arsenal starting in menacing mood, Ljungberg again gets forward to collect Bergkamp's pass but is denied by a brave save from James, who dives at the feet of the Swede as he is about to shoot from 12 yards out.
6 - Sinclair skips to the byline on the left and clips in a cross that Kanoute heads just wide of the target.
12 - After controlling Sinclair's crossfield pass on his chest, Schemmel collapses in agony with an apparent foot injury and is forced to leave the field for treatment.
14 - After Cole's jinking run on the left and low cross into the box, Kanoute sweeps a left foot shot just inches wide of the target.
17 - Substitution for West Ham, Labant replaces Schemmel.
18 - Edu's right foot shot from the edge of the box is deflected comfortably into the arms of James.
18 - Kanoute wastes a glorious chance to open the scoring as he takes advantage of some slack defending from Keown and Adams to skip between the two veterans but blasts his shot over the bar from just six yards out with only Seaman to beat.
21 - Parlour dispossesses Labant on the right and feeds Henry, who in turn slips a ball into the box for Ljungberg, but the Swede shoots wide of the far post.
35 - Edu's corner from the right is headed high over the bar by Vieira.
37 - Hammers are amazingly denied what should be a clear-cut opening goal. Kanoute races clear from Lauren and then rounds Adams and Seaman before slotting the ball goalwards. The ball clearly appears to have crossed the goalline before Ashley Cole slides in to clear but the referee's assistant unbelievably waves play on. TV replays immediately show that the whole of the ball was almost a foot over the line.
Added time: 4 minutes.
Half-time: Arsenal 0 West Ham United 0.
50 - Arsenal almost open the scoring with their first real attack, as Parlour races on to Bergkamp's pass but sees James smother his effort. The ball rebounds to Henry, who can only hit his shot against the grounded Hammers' keeper and the ball is cleared.
55 - Ljungberg cuts in from the left and blasts a low shot that is comfortably held by James.
56 - Carrick booked for foul on Vieira.
57 - Henry's curling free-kick from the left-hand edge of the penalty area bends just wide of the far post.
63 - Edu booked for foul on Kanoute.
64 - Substitution for Arsenal, Kanu replaces Edu.
67 - Bergkamp's curling left-foot effort from 25 yards out whizzes dangerously past the post.
73 - Arsenal carve the Hammers open with a delightful move and Parlour's cross from the right appears to be dropping on the head of Henry six yards out, until Pearce rescues the situation with a clearing header.
74 - Substitution for West Ham, Defoe replaces Kanoute.
77 - GOAL. Arsenal's second half dominance finally pays off as they take the lead with just 13 minutes remaining. Bergkamp is the predictable instigator as he cuts in from the right and threads an inch-perfect pass through the middle for Ljungberg to slide home from 12 yards out. Arsenal 1 West Ham United 0.
80 - GOAL. The Gunners extinguish any lingering hopes of a Hammers comeback as Ljungberg dispossesses Sinclair on the left and skips down the flank before hooking over a deep cross to the far post, where Kanu is waiting to volley the ball into the roof of the net from eight yards out. Arsenal 2 West Ham United 0.
81 - Substitution for Arsenal, Grimandi replaces Bergkamp.
89 - Vieira booked for foul on Labant.
Added time: 2 minutes.
90 - Lomas booked for foul on Ljungberg.
90 - Substitution for Arsenal, Dixon replaces Ljungberg.
Full-time: Arsenal 2 West Ham United 0.