Claudio Marchisio was also on the scoresheet as the champions came from a goal down to move within one win of retaining their Scudetto crown.
Simone Zaza handed the relegation-threatened hosts a shock lead after just nine minutes, but Carlos Tevez rifled home an effort 10 minutes before the break to restore parity.
Claudio Marchisio's clever close-range finish put Juve in front just after halftime and Fernando Llorente's brilliant back-heeled finish 15 minutes from time sealed victory for Antonio Conte's side at a rain-soaked Citta del Tricolore.
With three games remaining, the champions now hold an eight-point lead over Roma, while Sassuolo remains above the drop zone only thanks to its superior head-to-head record with Bologna.
Victory for Juve is another step toward a third consecutive Scudetto, and Conte's men will finish the job if they beat Atalanta at home in seven days' time, or if Roma fails to win at Catania 24 hours earlier.
Juve made an uncharacteristically slow start to the game and Nicola Sansone flashed a shot narrowly wide in the second minute before setting up the opening goal seven minutes later.
Sansone supplied strike partner Zaza, whose shot took a deflection off the foot of Angelo Ogbonna and skidded off the wet surface before creeping under the body of Gianluigi Buffon at the near post.
It took until the 22nd minute for Juve to muster a meaningful effort, Tevez firing a volley wide of the left-hand post after being teed up by Giorgio Chiellini.
It was Argentine Tevez who leveled matters 10 minutes before the break, finding a pocket of space on the edge of the box and unleashing a shot that whistled beyond Gianluca Pegolo via a slight deflection off Alessandro Longhi.
The hosts responded strongly, Zaza forcing a fine save out of Buffon at the near post as Sassuolo ended the first half with a flourish.
The home side's positivity was punctured 13 minutes after the interval, however, as Marchisio caressed a low finish beyond Pegolo after being picked out by Pirlo's deft chip over the Sassuolo back line.
Marchisio stung the palms of the goalkeeper 10 minutes later from Paul Pogba's lay off, while Tevez struck the crossbar with a curling effort 13 minutes from time.
Juve did claim the third goal that its second-half dominance merited when Llorente turned home substitute Stephan Lichtsteiner's cross in the 76th minute with a delightful back heel.
Conte's focus will now shift to overturning a 2-1 deficit in Juve's Europa League semifinal second leg at home to Benfica on Thursday.