Scorers: Arsenal - Welbeck (22, 30, 52), Sánchez (41); Galatasaray - Yilmaz (63, pen)
Bookings: Arsenal - Szczezny (red card)
With England manager Roy Hodgson watching from the stands, Welbeck, the £16 million deadline-day signing from Manchester United, produced a clinical display to put the Gunners back on course for qualification from Group D and mark manager Arsene Wenger’s 18th anniversary in style.
However, Uefa is likely to launch an investigation into the unsavoury scenes 20 minutes into the match which saw play halted after several flares were jettisoned from the away end, with Galatasaray goalkeeper Fernando Muslera and captain Wesley Sneijder helping restore calm as riot police surrounded the perimeter fences.
After a positive start and then surviving a couple of dangerous counter-attacks, Arsenal swept into the lead on 22 minutes.
Kieran Gibbs – another of several Arsenal players being watched by Hodgson in the stands – fed Alexis Sanchez on the left. The Chile international strode forwards, cut inside and then played a slide-rule pass through into the path of Welbeck, who held off Felipe Melo to guide the ball under Muslera.
It was soon 2-0. Aurelien Chedjou sent an attempted clearance header back towards goal, which Welbeck was on to in a flash, nodding it clear of Melo before sprinting to the edge of the penalty area, from where he dispatched a low shot into the bottom right corner.
Galatasaray fans then let off several flares and threw them on to the pitch which saw the game halted for several minutes, and could lead to disciplinary action from Uefa once all of the reports are gathered. The visiting supporters were, however, left in stunned silence after the start as Sanchez swept in a third goal. The Chilean, a £32 million summer signing from Real Madrid, showed no ill effects of Melo’s brutal challenge as he collected Mesut Ozil’s pass which split the defence to slot in his fifth goal of the season on 41 minutes.
Arsenal continued where they had left off following the restart and it was a neat through ball from England midfielder Alex Oxlade-Chamberlain that released Welbeck for his hat-trick on 53 minutes.
The striker clipped his shot over the keeper before taking in the adulation of the Arsenal supporters.
The hosts had to play out the final 30 minutes with only ten men after Wojciech Szczesny upended Burak Yilmaz as the Turkish forward beat the offside trap to dart onto a through ball. The referee immediately pointed to the spot, and brandished a red card.
Sanchez was the player substituted as Ospina, signed from Lille in the summer, came on, but the Colombian goalkeeper was sent the wrong way by Yilmaz.
Arsenal: Szczesny, Chambers, Mertesacker, Koscielny, Gibbs, Flamini, Cazorla, Oxlade-Chamberlain (Rosicky 68), Ozil (Wilshere 76), Sanchez (Ospina 61), Welbeck. Subs not used: Podolski, Campbell, Coquelin, Bellerin.
Galatasaray: Muslera, Kaya, Felipe Melo, Chedjou, Sari (Bulut 68), Kurtulus (Altintop 46), Sneijder, Dzemaili, Alex, Burak Yilmaz, Pandev (Bruma 68). Subs not used: Bolat, Balta, Adin, Camdal.