Mikel Arteta made five changes for the visit of the Blades and it was Nketiah – in for the injured Gabriel Jesus – who proved the difference and ended a memorable afternoon wearing the captain’s armband.
Martin Odegaard dropped to the bench in the most eye-catching of Arteta’s alterations, which also saw Emile Smith Rowe make his first league start since May 2022.
The victory took Arsenal up to second place, two points behind leaders and north London rivals Tottenham as Arteta’s men remained unbeaten after 10 league games.
For the Blades, this was a galling afternoon where – once their resolute defence was breached for the first goal just before the half-hour mark – the writing was on the wall.
The travelling fans sang the name of under pressure manager Paul Heckingbottom but they have still yet to see their team win on their return to the top-flight, with just one point on the board.
With Jesus facing a few weeks out with a hamstring issue, Nketiah has once again been tasked with filling his boots as Arsenal’s go-to centre-forward.
His touch and finish for the opening goal proved he can do the job as the England international set the Gunners on their way to a comfortable victory over the rock bottom Blades.
The second goal arrived five minutes after the interval, Foderingham this time flapping at a Bukayo Saka corner with the ball dropping to Nketiah, who arrowed a shot into the top corner. A VAR check for a potential foul on the United goalkeeper failed to save the visitors.
Nketiah, who made his England debut of the bench in 1-0 friendly win over Australia earlier this month, saved the best for last.
Collecting a pass from Smith Rowe, the 24-year-old rifled home from 20 yards to complete his hat-trick.
Saka, captain in the absence of Odegaard and Jesus, was replaced soon after and – to cheers from the home supporters – gave the armband to Nketiah.
But instead Vieira dusted himself down to send Foderingham the wrong way and further extend the lead.
Tomiyasu rounded off the scoring deep into added time after Mohamed Elneny’s flick on from a near-post corner was deflected into the path of the Japan defender.