The Gunners had scored in each of their 14 Premier League matches since a 2-0 loss to Manchester City in their opening fixture, but they were frustrated by a stubborn Huddersfield side until Torreira's strike late on.
Pierre-Emerick Aubameyang, who had missed a great chance in the first half, provided the assist with a chip into the middle that an unmarked Torreira acrobatically fired in.
Arsenal moved up to third with the victory while Huddersfield dropped into the relegation zone.
Alexandre Lacazette and Aubameyang were paired together and both strikers spurned clear chances within a minute just before the half-hour mark.
Aubameyang directed Granit Xhaka's attempted shot wide before Lacazette slipped and fired over when found by Matteo Guendouzi.
Referee Paul Tierney handed out seven first-half yellow cards – five of those shown in as many minutes – and Arsenal felt further injustice when Lacazette was denied the opener having been adjudged offside, though the flag only went up after Huddersfield's Mathias Jorgensen had touched the ball.
As he did against Tottenham, Arsenal boss Unai Emery made a double switch at half-time as he brought on Henrikh Mkhitaryan and Alex Iwobi.
Huddersfield were also forced into two alterations in quick succession due to injury, and between the two substitutions Alex Pritchard was denied a penalty when he claimed Hector Bellerin clipped him.
Shkodran Mustafi then picked up an injury and forced Emery into a final change in the 66th minute, and the alternations contributed to Arsenal's lack of fluency.
Yet seven minutes from time Torreira finally broke Huddersfield's resistance.
Aubameyang brought down Guendouzi's ball in the box and though his initial effort was blocked by Terence Kongolo, the Gabon international spotted Torreira and lifted the ball into the midfielder to smash in an emphatic winner.
What it means? Below-par Gunners march on
Arsenal were brilliant when they beat Tottenham in the north London derby but Huddersfield kept them at bay until late on. Yet the best sides win even when they do not play well and ultimately that is what Emery's side did.
Match-winner Torreira shines again
Six days after scoring a crucial goal against Spurs, Torreira found the net again at home. He is proving to be crucial for Emery and looks like one of the signings of the season.
Gunners punished for theatrics
Five Arsenal players received cautions and three of them – Xhaka, Mustafi and Guendouzi – were rightly booked for diving. Emery's team are winning admirers but they must cut the play-acting out to keep the neutrals on side.
Key Opta Facts
- Arsenal have not led at half-time in any of their 16 Premier League games this season, drawing 12 and losing four.
- Emery has made 14 substitutions before the start of the second-half in their 16 Premier League matches this season, more than any other side and five more than Arsene Wenger made with the Gunners in the whole of 2017-18 (9).
- Huddersfield have lost nine of their last 10 top-flight matches against Arsenal (W1), failing to score in each defeat.
- Aubameyang has been directly involved in 27 goals in his 29 Premier League appearances with Arsenal, scoring 20 and assisting seven.
Having already qualified for the Europa League knock-out phase, Arsenal round out the group stage against Qarabag on Thursday before hosting Southampton three days later, a game that Sokratis Papastathopoulos and Mustafi will now miss through suspension. Huddersfield entertain Newcastle United in the first of back-to-back home games before Christmas.