In his most entertaining act, Folau soared high to reel in a pinpoint crossfield kick from five-eighth Bernard Foley to touch down two minutes before the break.
It was his fourth try in his rookie Super season, and third in four games, but first straight from the rugby league playbook, with the Waratahs surprisingly slow to tap into the former Kangaroo's renowned aerial skills.
The conversion from Brendan McKibbin gave the home team their 15-point buffer as the Chiefs were kept scoreless for an entire half for the first time all season.
But the match turned two minutes into the second half when NSW lock Sitaleki Timani was yellow carded for a high tackle on Tim Nanai-Williams.
The Chiefs immediately capitalised on their one-man advantage with replacement fullback Gareth Anscombe crossing and converting his own try five minutes later.
A McKibbin penalty goal briefly gave the Tahs some breathing space before two replies from Anscombe nudged the Chiefs within five points of the locals.
The titleholders appeared to have stolen the points when prop Ben Tameifuna swivelled his way over under the posts and Anscombe slotted the extras to take a 20-18 lead with the clock winding down.
But with NSW's season on the line, Ulugia steamed onto a short ball from Foley to score the match-winning try that vaulted the Waratahs to seventh place on the ladder.
Fresh off the bye, the Waratahs made a vibrant start to the match with fullback Folau, centre Rob Horne and even prop Benn Robinson all finding themselves in open space in the early stages.
It seemed inevitable the Chiefs defence would crack and so it did when midfield star Adam Ashley-Cooper made All Blacks five-eighth Aaron Cruden look silly as he stepped inside him to put debutant winger Cam Crawford in for the opening try in the 14th minute.
After nailing an early penalty goal, McKibbin missed the relatively easy conversion attempt to leave NSW ahead 8-0 before Folau's heroics virtually doubled the Tahs' advantage.
The only downer for the Waratahs was the loss of injury-plagued Wallabies winger Drew Mitchell to another hamstring strain.
Chiefs fullback Andrew Horrell was another casualty, departing on a stretcher with what appeared a serious leg injury.
-AAP