Antonio Conte's side moved to 55 points after taking the spoils from an entertaining encounter in which Sampdoria showed great heart and plenty of attacking intent.
The Turin side restored their advantage over second-placed AS Roma, who briefly closed the gap to five points after strolling past lowly Livorno 3-0 earlier on Saturday with goals from Mattia Destro, Kevin Strootman and Adem Ljajic.
Vidal broke the deadlock in the 18th minute and, after Llorente powerfully headed home the second from a corner six minutes later, the Chilean midfielder took his tally to 10 goals for the season with a penalty four minutes before halftime.
The soft-looking spot kick was a blow for Sampdoria after Sinisa Mihajlovic's side had got back into the game three minutes earlier when Juve's Andrea Barzagli diverted Manolo Gabbiadini's low cross into his own net.
Sampdoria, who kicked off having only lost one league game since the Serb took over in late November, cut the deficit again in the 70th when Gabbiadini tapped in his fifth goal of the season on the rebound after an initial save by Gianluigi Buffon.
Three minutes later the forward almost equalised when he thumped a long-range shot against the bar.
Another huge sigh of relief went around a nervy Juventus Stadium with 12 minutes remaining when midfielder Pogba struck a powerful shot from distance that flew into the top corner.
Third-placed Napoli, 13 points off the pace, visit Bologna on Sunday, while former Netherlands international Clarence Seedorf returns to his old club to take charge of AC Milan for the first time against Hellas Verona at the San Siro.