Sami Khedira scored midway through the first half, and had should have had at least another goal to his name, before Cristiano Ronaldo got his 20th goal of the season with 20 minutes remaining. Substitute Emre Can rounded off the scoring late on.
It was a first win in three matches for Juventus following defeat at Atalanta in the Coppa Italia and the 3-3 home draw with Parma last weekend.
Sassuolo started well and thought they should have had a penalty after only five minutes when Wojciech Szczesny appeared to clip Filip Djuricic's foot, sending the attacker to the ground.
However, the referee decided against awarding a spot-kick after consulting VAR.
Stefano Sensi then had Szczesny scrambling across his goal shortly afterwards as his powerful shot flew narrowly wide.
Juventus struggled to get going early on and cheaply conceded possession on numerous occasions. Djuricic collected a loose ball, after Juventus had given it away again, and set up Manuel Locatelli, whose driven shot brought a decent save from Szczesny down to his right.
It was against the run of play when Khedira opened the scoring after 23 minutes. Ronaldo's long-range effort could only be parried back out by Andrea Consigli and Khedira was on hand to tap in the rebound from close range.
The goal seemed to spring the league leaders into life and Mario Mandzukic should have really done better than head the ball over the crossbar from Ronaldo's pin-point cross.
However, his miss was not as bad as that of Khedira at the end of the first half as the German midfielder somehow managed to head wide from inside the six-yard box.
Another headed chance was missed by the visitors at the start of the second half, this time Daniele Rugani was the culprit.
A mistake by Szczesny almost allowed Sassuolo back into the game after 55 minutes.
The goalkeeper came a long way out of his goal for a long ball forward but sliced his clearance straight to Domenico Berardi, who was unable to hit the unguarded net from 40 yards out.
Khedira missed another golden opportunity to extend the lead when he missed again from close range but Juventus eventually got their second goal with 70 minutes on the clock.
Miralem Pjanic swung in a corner and Ronaldo rose highest inside the penalty area to power home the header.
Now in complete control, the visitors were happy to just keep the ball and frustrate Sassuolo but they added a third goal four minutes from the end when Can rounded off a lovely passing move involving fellow substitute Paulo Dybala and Ronaldo.