By Chris Harris at Emirates Stadium
Theo Walcott scored a first-half hat-trick as Arsenal ended the Premier League season in spectacular style.
Walcott set the tone with a venomous strike that flew in off the underside of the crossbar. He followed that with a predatory finish before completing his treble with a tap-in - all in a matter of 32 minutes.
Jack Wilshere got in on the act with his own goal of the month contender, a crisp volley into the top corner from the edge of the box. And there could easily have been more as a beleaguered West Brom were cut to ribbons time and again by their rampant hosts.
Gareth McAuley headed a consolation for the visitors in a less eventful second half, but Arsenal had done more than enough to grant Arsene Wenger's wish and "send the fans home happy".
A carnival atmosphere was a welcome change to the nail-biting climaxes of recent campaigns. Arsenal have comfortably secured a top-three finish for the first time since 2012 and will not need to navigate a Champions League play-off at the start of next season.
What's more, this slick, satisfying display sets them up perfectly for next weekend's FA Cup final. Wenger has some serious thinking to do before picking his Wembley side.
SETTING THE SCENE
Wenger freshened up his team for the final home game of the season, making three changes to the side that played out a draw with Sunderland in midweek. In came Gabriel, Francis Coquelin and Walcott; Laurent Koscielny, Aaron Ramsey and Olivier Giroud dropped to the bench. Wilshere kept his place to make his 100th Premier League appearance.
There was a notable inclusion on the bench, Alex Oxlade-Chamberlain returning to the squad for the first time since March 9 after a groin problem.
A point would be enough for Arsenal to make sure of third place - although even a defeat would probably be enough given Manchester United's inferior goal difference. On the subject of goals, they had been in short supply at Emirates Stadium, Wenger's side failing to net in three consecutive home games.
West Brom had had no such problems, putting three past champions Chelsea in their last fixture. But history was against Albion - they had lost six and won none of their last seven league games against Arsenal.
The Emirates crowd had waited a while for an Arsenal goal and their thirst was quenched with one of the season's most spectacular strikes.
Walcott delivered it, drifting to the right of the penalty spot to collect a short pass and smash a thunderous shot beyond Myhill and in via the underside of the crossbar. The venom of Walcott's shot - generated with very little backlift - gave the keeper no chance.
Walcott wasn't done. Having reminded everyone of his power, he demonstrated his predatory instincts, latching onto a loose ball inside the box and quickly adjusting his feet to prod a low shot past Myhill.
West Brom could do little to stem the Arsenal tide as Wenger's side played with tempo and intensity, launching wave after wave of attacks.
The third goal was just around the corner, and it was a special moment for Wilshere.
A corner was cleared to the edge of the box and Gabriel teed it up for the England midfielder, whose volley from the edge of the box whistled into the top corner. Wilshere ran to the bench to celebrate with Declan Lynch, a member of the team who helped his rehabilitation from injury.
Alexis whipped a free-kick just over the bar and then teed up Walcott for a curler that Myhill did well to push aside, denying the Arsenal forward a hat-trick inside 23 minutes.
Walcott didn't have to wait long. He completed his treble in the 37th minute with a tap-in from a matter of inches after Santi Cazorla's cross eluded Myhill.
There could have been more before the break. Walcott shot wide just after his hat-trick goal, Wilshere fired straight at Myhill after a slick one-two with Alexis, and Per Mertesacker was denied by the West Brom keeper after meeting Mesut Ozil's low free-kick.
Predictably the second half failed to spark as West Brom opted for damage limitation and Arsenal dropped down a gear.
Cazorla brought a brilliant save out of Myhill seven minutes after the break with a curling effort from the edge of the area. Walcott reacted quickly but couldn't keep his effort down after reaching the rebound.
The visitors did restore some pride before the hour mark, McAuley beating David Ospina to Chris Brunt's corner to head into an unguarded net.
Walcott left the field to a standing ovation as Wenger gave Ramsey and Giroud a run-out. There was an even louder ovation with 13 minutes left when Oxlade-Chamberlain came on.
Arsenal were happy to keep the ball, keep West Brom at arm's length and hold onto the points that would ensure a first top-three finish for three years.
But they almost added a fifth when Ramsey collected Ozil's pass and thumped a shot against the far post. And Ramsey went close again with a deft clip which Myhill tipped onto the frame of the goal.
Referee: Robert Madley
Copyright 2018 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source.