The Giallorossi started their Serie A campaign with 10 straight wins only to come unstuck during their November draw with Torino and Juventus have since seized control of the table.
Mattia Destro's goal shortly before half-time in Rome was a positive step towards narrowing Juve' 14-point advantage, but Ciro Immobile soon rocked the Stadio Olimpico with a stunning volley.
The young striker's 17th goal of the season improved his chances of earning a place in Italy's World Cup squad yet, unfortunately for 10th-placed Torino, Florenzi snatched victory for the hosts at the death.
Visiting goalkeeper Daniele Padelli would have a busy evening and within minutes he was blocking a daisy-cutter from Miralem Pjanic.
Leandro Castan blocked Immobile's shot at the other end before Destro came dangerously close to scoring with a header from Radja Nainggolan's cross.
Destro had an even better chance in the 23rd minute, this time nodding wide of the mark from Francesco Totti's spilled corner.
Roma soon began to turn the screw. A splendid move started by Maicon saw Daniele De Rossi attempt a bicycle kick and, when that brave effort missed, Totti rifled a low drive straight at Padelli.
Alessio Romagnoli tried his luck from outside the area before Torino bit back, Immobile's searing angled effort whizzing just past a post.
But Roma were always on top and, after Padelli made a quick double save on Destro and Pjanic, the former striker found a way through.
Four minutes before the break Gervinho shrugged off several defenders to pick out Destro and he slid in to clip beyond the onrushing Padelli.
Roma fancied hitting their opponents with a second goal as soon as play resumed but Padelli was equal to Gervinho's close-range shot.
It came as some surprise, then, as Torino managed to level the match in the 52nd minute.
Seizing onto an inspired pass from Giuseppe Vives, Immobile scored his ninth away goal of the season by bamboozling Morgan De Sanctis with a stunning volley.
Roma pushed back and could have restored their lead through Pjanic, who tried to surprise Padelli with his less-favoured right boot.
Yet another swift counter-attack from Torino saw Jasmin Kurtic feed Alessio Cerci in the penalty area, the Italy winger's attempt veering wide of the mark.
It was nearly 2-1 Roma when Maicon eluded Matteo Darmian to set up Gervinho.
The Ivorian clipped wide from a good position and substitute Adem Ljajic's free-kick barely worried Padelli.
Roma debutant Rafael Toloi looked like winning it for the hosts late on, his blast from 30 metres forcing Padelli to fumble the ball, but it was substitute Florenzi who won the day.
One minute into stoppage time, the midfielder collected Gervinho's slide-rule pass and turned the ball coolly past Padelli to spare Roma's blushes.