La Viola's eighth win tightened their grip on fifth place and took their points tally to 27, equal with fourth-placed Inter but ten points behind leaders Juventus.
Borja Valero scored the first of his brace when he collected the ball from the right and was given the freedom to cut across the edge of the area and beat Verona 'keeper Rafael with a bouncing left-foot shot.
The hosts' joy was short-lived, however, and when Juan Iturbe forced a rebound from Neto with a drive from distance Romulo beat Fiorentina's defence to the rebound and beat the 'keeper with an angled shot from close in.
Valero narrowly missed restoring Fiorentina's lead when he ran on to a long ball from midfield and through the Verona defence, only to lob his shot over the crossbar before Massimo Ambrosini sent a header wide of the upright.
But a minute later, Iturbe stunned Neto from 25 metres when he collected Luca Toni's lay-off on the right before slamming a left-footed strike inside the keeper's near post.
Fiorentina, however, were back on level terms only a minute later after Valero danced past a throng of defenders on the edge of the area before beating Rafael with the help of a deflection from diving defender Domenico Maietta.
Fiorentina went in at half-time 3-2 to the good after yet another long-range strike, this time courtesy of Peruvian midfielder Juan Vargas, who slammed a left-foot strike under Rafael from the left of the area.
And the hosts were two in front shortly after the restart when, following Bosko Jankovic's expulsion for handling in the area, Giuseppe Rossi beat Rafael from the penalty spot to take his league-leading tally to 12 from 14 games.
To their credit, Verona made light of their disadvantage and after Toni had tested Neto down low, Jorginho reduced arrears in the 72nd minute with a drive from the edge of that was beyond the Brazilian keeper's reach.
Napoli's tenth win left them in third spot but after Roma's fourth consecutive draw on Sunday, Rafael Benitez's men are now only three points behind the Giallorossi and six off leaders Juventus.
With only one win against Napoli in their last five games, and having taken only eight points in their last eight outings, Lazio were desperate for a morale-boosting first success since a 2-0 defeat of Cagliari at the end of October.
But despite containing Napoli in a balanced first half, the Biancocelesti were punished after the break when Goran Pandev and Higuain struck in clinical fashion to give the visitors a 3-1 lead 18 minutes from time.
Despite reducing the arrears two minutes from time thanks to teenager Keita Balde, slack defending allowed Jose Callejon to hit Napoli's fourth in injury time to send Lazio down one place to ninth, with AC Milan moving up to eighth.