The Chilean star hit a beauty to give Juve victory in a disappointing derby and the Serie A holders need just one point from the last four games to assure title success
Juve shaded the match in terms of territory and possession, but were imprecise in attack and rarely threatened to break the deadlock, breaking through with just four minutes left when Vidal smashed home a volley from nowhere.
With Torino demoralised, Claudio Marchisio deepened the wound with a second in injury time to assure victory.
The win means that Conte's charges lie eleven points clear at the top, with Napoli trailing in second. A victory or draw in the next round against Palermo would ensure that the title will be staying in Turin for another year. Torino, meanwhile, let slip a valuable point that leaves them just four clear of the relegation zone.
The first half was accompanied by strong rain and a grey panorama in Turin, and although it did little to dampen the spirits of the home support, the conditions made it difficult for either side to control the tempo and pass fluidly across the pitch.
In a tight first 45 minutes, Juve had a handful of chances to put themselves in the lead and further extend their advantage at the top. Mirko Vucinic should have done a lot better after being played through by a sumptuous ball from Paul Pogba. The Montenegro striker had the net firmly in his sights, but failed to make decent contact on a greasy surface and ended up steering a tame shot wide of the post.
Vidal was another man to go close for the Old Lady, steering a header high and wide after connecting with Stephan Lichtsteiner's cross at the far post.
The game began to open up towards the end of the period and the visitors thought they had scored when Marchisio broke through and chipped past Jean-Francois Gillet, but the flag soon went up as the midfielder was comfortably offside when fed by Vucinic.
Torino, meanwhile, attempted to hit their rivals on the break but had few opportunities to do damage and break a run of seven games without scoring in a derby.
Mario Santana went closer than anybody in burgundy, releasing a terrific shot from outside the area that needed an equally wonderful stop from Gianluigi Buffon to ensure the sides would go into the break still deadlocked.
The second 45 minutes started in a rather scrappy fashion, with neither side holding back in the tackle resulting in plenty of fouls and pauses in play.
Neverthless, Vucinic went close to opening the scoring with a rather fortunate effort, a shot that took a big deflection off the boot of Migjen Basha and landed inches wide of the post.
Juventus stayed on top, dominating possession, but they could not find any way past a home team that compensated for their deficiencies with no little commitment and enthusiasm.
Lichtsteiner summed up the frustration of his team-mates with a speculative shot from outside the box that flew wide, an indication of the solidity of Torino at the back as Juve were starved of space.
Antonio Conte rang the changes to attempt to find a winning formula, and with just four minutes to go, a moment of magic broke down the home resistance.
Vidal looked to be innocuous enough as he received the ball well outside the Toro area, but the Chilean released a stunning volley that squeezed into the net and earned the three points in dramatic fashion.
It was heartbreak for Torino after such resistance, getting worse at the end when Kamil Glik was expelled for a second booking, and any hopes they may still have had evaporated when Marchisio turned in a corner in injury time to end the game as a contest.