The 24-year-old striker netted the first treble of his career to end Torino's four-match losing streak and keep Livorno very much in danger of relegation to the second tier.
Immobile opened the scoring after 25 minutes when he flicked home Cesare Bovo's near-post free-kick, and he doubled the lead with a scuffed half-volley on the hour mark following neat link-up play with Omar El Kaddouri.
The former Genoa man then capped off a fine performance seven minutes later, scoring his 16th league goal of the season with a fierce right-footed effort from distance.
Livorno did net a late consolation through Luca Siligardi but they are just a point above the relegation zone.
Meanwhile, Roma cemented their grip on second place with a comfortable 2-0 victory at Chievo.
Former Arsenal forward Gervinho gave the visitors the lead as he found the net for the ninth time in all competitions after 17 minutes.
The Ivorian capitalised on a terrible defensive header from Bostjan Cesar by volleying past helpless Chievo goalkeeper Michael Agazzi.
Rudi Garcia's side were always in control and they sealed the points three minutes before half-time, attacker Mattia Destro coolly slotting home from Brazilian midfielder Rodrigo Taddei's expertly placed throughball.
Gervinho went close again with a late header that was brilliantly saved by Agazzi, but it mattered little as the visitors comfortably closed out the game to move six points clear of third-placed Napoli ahead of their meeting with Fiorentina on Sunday.
