The Argentine put the Viola on their way to ending its winless streak with an effort from his own half, but the Partenopei talisman's 100th Serie A goal shared the spoils.
Facundo Roncaglia put the Viola in the driver's seat with a spectacular opening goal midway through the first half, but Edinson Cavani found the back of the net for the 100th time in the Italian top flight just before halftime to extend the hosts' winless run to four matches.
The Viola took the lead on 33 minutes in astonishing circumstances when Roncaglia, in the center circle, clipped a ball forward from his own half that inexplicably looped over goalkeeper Morgan De Sanctis and two Napoli defenders.
Nine minutes later, Marek Hamsik sent a flighted free kick into the box, and Cavani was on hand to glance the Slovak's attempt past Neto for his landmark tally, extending his lead for the Serie A golden boot. It was a welcome contribution from the Uruguayan, who was quiet for most part.
De Sanctis then came close to making his second howler of the afternoon as another loose ball near his goal was poorly managed by the Italy goalkeeper, but he eventually smothered the danger in a crowded box.
On the cusp of halftime, the Viola came close to retaking their lead. Juan Cuadrado, a constant thorn down the right flank, overlapped Juan Zuniga and drilled a cross into the box, but Luca Toni, despite his cavalier movement, struck over the bar.
On the hour mark, both goalkeepers were forced to stay on their toes. Hugo Campagnaro slipped through Cavani, who saw his finish saved by Brazilian shot-stopper Neto at his near post, before Alberto Aquilani saw a mirror image denied.
Neto arguably saved Fiorentina a point with less than 10 minutes to go when he produced a fine stop to claw away Miguel Britos' header. Stevan Jovetic then could have volleyed his side toward victory in stoppage time, but his effort whistled just wide.
The Tuscans continued to apply the pressure in the latter stages, and they seemed to have found the winner when Cuadrado cut the ball back for Aquilani, who was unmarked on the edge of the box, but the midfielder struck over the bar.
The result leaves Napoli tied with Lazio but still one place shy of leaders Juventus in the Serie A standings. Fiorentina, however, is now without a win in three league games and fell seven points off the pace in the race for a Champions League spot.