Luciano Spalletti's men returned to winning ways over the weekend with a 1-0 triumph over Sampdoria, and they looked build on that win to close the gap on Juventus and Napoli.
The hosts were in control from the onset and managed to carve out a chance through Antonio Candreva, who volleyed just over the crossbar, although Fiorentina's Kevin Mirallas
Giovani Simeone, the son Atletico coach Diego, had a glorious chance to put Fiorentina ahead after 32 minutes when he was left one-on-one with Samir Handanovic, who made the save to deny the Argentine.
Inter eventually got the breakthrough on the stroke of the half when the Video Assistant Referee showed Vito Hugo handling the ball in the box, which led to a penalty.
Mauro Icardi stepped up and calmly slotted home from 12-yards out for his first league goal of the season.
Fiorentina were level ten minutes into the second half when Federico Chiesa's shot took a deflection off Milan Skriniar and sailed into the back of the net.
Inter restored their lead in the 77th minute as Icardi turned provider to play in D'Ambrosio, who found the back of the net with a neat finish.
The hosts managed to see out the remaining stages of the encounter to claim a second successive league win.