The Argentinian scored twice in the first half before adding a fortuitous third just past the hour as the Blues moved to within two points of leaders Liverpool and back into second spot above Spurs.
Arsenal had survived an opening blitz from City to level early on, but were eventually overwhelmed by incessant attacks from City and were ultimately lucky not to lose by more than the 3-1 scoreline.
City tore out of the blocks looking like a team who wanted to prove a point.
The midweek loss to Newcastle hurt - but Leicester’s surprise draw at Anfield 24 hours later gave the Blues an unexpected fillip and it took just 46 seconds to turn disappointment into delight.
Arsenal seemed to have cleared the danger from City’s first attack, but Aymeric Laporte won possession on the corner of the Gunners box, whipped in a cross and Aguero stooped to head home his 18th of the season.
You wait for a goal in the first minute for six years and then, like buses, two come along in succession and both by the same player!
The Blues were then denied a clear penalty just three minutes later as Aguero was tugged back in the box by Shkodran Mustafi, but referee Martin Atkinson said nothing doing – it looked a nailed-on spot-kick and is yet another advocate for VAR which would surely have overturned the ref's decision.
Then Raheem Sterling sent a pile-driver in that was clawed away by Bernd Leno and moments later Kevin De Bruyne’s free-kick was powered home by Laporte – only tor the Frenchman's effort o be flagged marginally offside – in a crazy opening 10 minutes.
Football being football, the battered and bruised Gunners then levelled from their first attack – a flicked on corner that allowed Laurent Koscielny a free header in the six-yard box.
It was harsh on the Blues who had played some sparkling stuff that deserved better, but it’s how things have been going this season, with Lady Luck deserting the champions on more than one occasion.
Not much of note happened at either end for the next 30 minutes or so until the 43rd minute when City retook the lead.
Ilkay Gundogan spotted Sterling’s clever run into the box, lofted a deft ball into his path and the England winger’s sublime first-time cross was tapped in at the far post by Aguero.
In many ways, it was a huge relief with some of the intervening play a tad scrappy end edgy – it was crucial to the champions’ confidence that the next goal came from a player in sky blue, and it had.
De Bruyne’s vicious low cross came close to adding another seconds before the break as the Blues ended the half strongly.
And the champions began the second period as they ended the first, looking for the breathing space of a two-goal cushion to calm the nerves in the stands - and it arrived just past the hour.
Sterling ran into the box and with no challenge, continued on before sliding another fine cross into the middle that Leno pushed onto the upper half of the sliding-in Aguero's body and the ball trickled over the line.
It was a bizarre way to complete yet another Aguero hat-trick, but nobody was complaining!
It was no more than City deserved and Aguero, De Bruyne and David Silva all went close to increasing the lead against the Gunners thereafter, but a mixture of good goalkeeping, near-misses and missed opportunities ensured the score remained 3-1 to City.
What it means…
The Blues move back into second, two points behind Liverpool who take on West Ham at the London Stadium on Monday evening.
Star man: Sergio Aguero
Who else? Yet another world class display of finishing, opportunism and hard work by our talisman striker.
“Unfortunately, we don’t have a week off. We now rest and prepare for Goodison Park. I cannot deny I would want West Ham to beat Liverpool - Liverpool would want Arsenal to beat us.
“Of course, we have to win. After the Newcastle defeat everyone thought we would go seven behind. A lot of things will happen between now and the end of the season. We scored first and kept trying for more, that’s the biggest lesson we can learn.
“Many things can happen. If it’s seven points, it’s difficult but football isn’t like this. Now it’s two, tomorrow could be three or five again. We have to go to Goodison and get three more point.”
No time to catch breath as City travel to Goodison Park to take on Everton on Wednesday – then it’s another tough-looking home game against Chelsea.