Simone Zaza put the relegation-threatened side ahead in the ninth minute only for Juve to equalise shortly after when Carlos Tevez's effort deflected off Sassuolo defender Andrea Longhi for an own goal.
Claudio Marchisio put Juve in front before the hour mark and team-mate Fernando Llorente killed the game off with 14 minutes remaining as the Turin giants moved eight points clear at the top of the table with three games left.
Juve will now claim the scudetto if Roma fail to win at Catania on Sunday or if they win at home to Atalanta in their next game.
Sassuolo hold the last position of safety, but are level on 28 points with 18th-place Bologna, who are in the relegation zone.
Despite his team needing to overturn a 2-1 deficit against Benfica in Thursday's Europa League semi-final return leg, Juve coach Antonio Conte fielded his strongest side against a Sassuolo outfit that had collected seven points from their last three games.
The home side pressed from the start.
They grabbed the lead when Zaza's left-footed strike from 20 yards glanced off Juve defender Angelo Ogbonna and then beat goalkeeper Gianluigi Buffon.
Sassuolo sought a second goal, with Buffon holding a long-range effort from Floro Flores.
Juve put their best move together midway through first half when Giorgio Chiellini sent Tevez through and his right-footed strike went just wide of the far post.
There was nothing Sassuolo goalkeeper Gianluca Pegolo could do to deny Juve the equaliser in the 35th minute.
Tevez's right-footed effort from just outside the area took a heavy deflection off Longhi to beat Pegolo.
The hosts almost went back in front before half-time when Zaza got past Ogbonna and drilled in a left-footed shot from the heart of the area that was met by a fine save from Buffon.
Juve came to life after the restart and in the 52nd minute Pegolo kept out Tevez's goal-bound attempt.
Shortly after, Ogbonna headed Andrea Pirlo's cross just wide as Juve got closer.
The visitors were rewarded in the 58th minute when Pirlo set up Marchisio in the area and the Italian midfielder struck the ball towards the bottom right corner and out of Pegolo's reach.
Tevez was unlucky not to make it 3-1 in the 73rd minute when his right-footed volley beat Pegolo, but struck the crossbar.
Juve grabbed a third three minutes later when Llorente scored with a backheel from Stephan Lichtsteiner's low cross.
Sassuolo could not find a way through as Juve held on for a vital win.