Immobile was on target with a pinpoint header in the 25th minute, a scuffed volley on the hour and a stunning long-range strike to make it 16 league goals in 26 appearances and overtake Juventus forward Carlos Tevez (15) as top scorer.
The 24-year-old's goals were Torino's first in four games and broke a four-match losing streak that was threatening to derail an exciting season for Giampiero Ventura's side.
"Not even when I was at Pescara (in Serie B) did I score three goals in a game," said Immobile. "I'm proud to have done it and for all that we have done this season - the team, the manager, the club.
"(Italy coach Cesare) Prandelli knows how much effort I put into everything I do. If he decides to call me up I'll give my all," he added of the World Cup in Brazil in June.
Torino are ninth on 39 points, eight behind fifth-placed Inter Milan, and their chances of European football next season still look slim.
Luca Siligardi's 89th-minute goal was little consolation for a dismal Livorno who stayed one point above the relegation zone in 17th spot.
AS Roma hope to strengthen their grip on second place with a win at struggling Chievo Verona in Saturday's late game.
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- Carlos Tevez
- Giampiero Ventura