The Zebras came flying out the traps and were ahead within 11 minutes, when Christian Kabasele’s late run into the box went unnoticed, allowing him to head home Nicolò Zaniolo’s cross from close range.
That was the perfect start for a side who had only scored two first-half goals across their previous six matches.
Their opponents were in no mood to fold without a fight, though, and created a couple of chances for Rolando Mandragora, although he failed to hit the target on each occasion.
Keinan Davis and Zaniolo could have extended the hosts’ lead, but the former had his shot saved before the latter blazed over from a good position.
The Viola, 5-1 victors when these sides met in December, were then left frustrated at Jack Harrison missing a header, before Mandragora spurned a further opening as it remained 1-0 at the break.
Paolo Vanoli would have wanted more from his side going into the second half, but Kosta Runjaić’s men - who had lost their three previous outings - continued to impress, with Davis wasting another chance.
The forward would not make the same mistake next time though, coolly doubling his side’s lead with a penalty that he won himself after a foul by Daniele Ruganiiano.
Fiorentina needed to respond quickly, but for all the balls they launched into the box, few picked out a forward, apart from one, which Cher Ndour flicked wide.
Roberto Piccoli also missed the target as time ran out for the visitors, whose two-match winning run comes to an end, leaving them outside the relegation zone only on goal difference.
Udinese, on the other hand, made the win even more emphatic through Adam Buksa’s whipped finish from inside the area in injury time, capping off a victory at home for just the second time in six attempts.
Flashscore Man of the Match: Nicolò Zaniolo (Udinese)