The Gunners dominated the first half but were frustrated against a resolute visiting side. Strikers Pierre-Emerick Aubameyang and Alexandre Lacazette both wasted fine chances, and the Frenchman also had an effort ruled out for offside.
Torreira also came close to breaking the deadlock just before half-time. The Uruguayan's fierce shot from range looked to be heading for the top corner until a diving Jonas Lossl managed to tip it around the post.
Unai Emery made a double change at the break, sending on Alex Iwobi and Henrikh Mkhitaryan, but still Arsenal toiled against the Terriers.
They had to wait until the 83rd minute to finally break the deadlock, with Aubameyang crossing for Torreira to acrobatically volley home and secure the win.
Torreira Proving He's the Signing of the Season
Arsenal looked on course to drop points for the second match in a row on Saturday, until Torreira popped up late on with a brilliant goal to get them back to winning ways.
It was an impressive strike from the 22-year-old, too. He was the most advanced Arsenal player when Aubameyang knocked the ball into the penalty area, and the Uruguayan finished expertly:
The midfielder now has two goals and an assist in his last three Arsenal outings and is becoming increasingly influential in his first season in the Premier League.
The goal capped another outstanding performance from Torreira, who is proving to be exactly the type of player Arsenal needed in their midfield.
His energy, drive and tenacity are qualities Arsenal have been lacking for some time, and he is now making vital attacking contributions.
Arsenal signed Torreira from Sampdoria in July for a fee in the region of £26 million, according to Husmukh Kerai at Sky Sports.
Football writer Layth Yousif thinks he's in line for greater recognition:
Torreira already looks like being a bargain signing by Arsenal, and they will be hoping there is still plenty more to come from the midfielder as the season progresses.
Huddersfield's Time-Wasting Tactics Won't Keep Them Up
Huddersfield did their best to frustrate Arsenal in a feisty game at the Emirates. The visitors made life difficult for Emery's men and ensured it was a busy afternoon for referee Paul Tierney in the first half:
It was a similar story after the break for Huddersfield, who showed little ambition at the Emirates. Arsenal found it difficult to break down their five-man defence until Torreira finally grabbed a late winner.
Opta noted the lack of shots on goal during the match:
Huddersfield rarely threatened the Arsenal goal but might have got something out of the game if they had showed more ambition, according to writer Jonny Singer:
Yousif offered his view on the Terriers:
Huddersfield were rightly lauded for managing to avoid relegation last season. They beat Manchester United and managed draws against Manchester City and Chelsea on their way to survival.
Saturday's result drops them back in the bottom three, and if they are to stay up once again, they need to focus more on their football than frustrating the opposition.
Arsenal are back in action on Thursday in the UEFA Europa League when they take on Qarabag. Huddersfield Town host Newcastle United next in the Premier League on Saturday.