The powerful front man, snapped up from Shrewsbury , showed why boss Bryan Gunn had shelled out a six-figure fee for him with a clinical treble in the final 26 minutes.
Wes Hoolahan had begun the rout with a 55th minute penalty before Holt took over to become a firm favourite with the City fans.
After their 7-1 hammering on the opening day boss Gunn rang the changes with five players paying the price for the horror show.
And Gunn would have been thrilled with the Canaries start as former Dartford striker Cody McDonald headed Simon Whaley's cross just wide in the second minute.
McDonald then flashed a shot wide of Alex McCarthy's goal before Yeovil threatened in the 20th minute as Scott Murray's shot was deflected wide by Jen Berthal-Askou.
Murray then came to his side's rescue nine minutes before the break when he somehow cleared Michael Spillane's powerful shot off the line.
Having survived that let off the Glovers could have nicked the lead on 42 when Gavin Tomlin raced clear but on-loan Tottenham keeper Ben Alnwick got down well to save.
But the Canaries fans finally had a smile on their faces ten minutes after the break when they went in front from the spot.
Adam Drury's rampaging run into the box was ended by George O'Callaghan and former Blackpool winger Hoolahan stepped up to bury the penalty into the bottom corner.
The goal seemed to break Yeovil's resistance and Norwich doubled their lead in the 64th minute.
Whaley's cross into the box found Holt and he rose highest to head past the exposed McCarthy.
Holt obviously had the taste for it and he had a second eight minutes from time when Tom Adeyemi's shot was parried by McCarthy and the journeyman striker fired in the rebound.
Holt completed his haul when he curled past the despairing McCarthy in the final minute.