Despite Newcastle leading early and then late on Sunday afternoon at Mount Smart Stadium, Hoffman's 73rd-minute effort ensured a continuation of the Knights' losing streak, going back to round six of the 2016 season.
Taking advantage of an earlier break through the middle by new captain Roger Tuivasa-Sheck, the old skipper rode three markers across the line.
The four-pointer masked a near-collapse by the Warriors, who wasted a 20-8 second-half lead to head into the final stretch two points down.
Centre David Fusitu'a had scored a first-half hat-trick to put his side in prime position, only for the Knights' Jack Stockwell and Nathan Ross to turn the match around.
After dominating the first 10 minutes, the Warriors gave up the simplest of four-pointers to Knights centre Peter Mata'utia.
Rookie five-eighth Brock Lamb put up an innocuous bomb, only for the Warriors to watch as Mata'utia pinched the ball out of the air to score.
A Knights penalty goal for an 8-0 lead preceded some class from Shaun Johnson, who put the Warriors on the scoreboard in the 26th minute and the floodgates opened.
The 26-year-old, receiving the ball on the right, cut out one defender with a dummy before putting Fusitu'a in to score.
The try appeared to transform the hosts, with Solomone Kata bagging a second and Fusitu'a securing his hat-trick via two genius assists.
For the first, an outstretched Tui Lolohea rose highest to palm a deep crossfield kick back to Fusitu'a in the 37th minute.
Johnson then took on the Knights' line in the final play of the half and released a flick offload, which Fusitu'a gobbled up on the buzzer.
Up 20-8 at the break, the Warriors looked likely to plough on but stumbled after Simon Mannering's departure with a neck issue.
Repeated Knights sets of six on the Warriors' line resulted in Stockwell breaking through to score, before the Knights put themselves within two in the 62nd minute.
Halfback Trent Hodkinson played the ball to the left edge, where winger Ross brushed off the last-gasp tackle of Johnson to score.
They then edged in front four minutes later as Ross bagged a second, but couldn't contain a determined Hoffman at the death.
The loss will also be made worse for the Knights by an apparent serious knee injury to fullback Dylan Phythian.
The Auckland-based side managed to snap a seven-year winless streak in round-one matches.
The Warriors next week face last year's grand finalists Melbourne, while the Knights will play Gold Coast.