The substitute's last-gasp winner broke the visitors' hearts after a superb defensive display had frustrated Antonio Conte's team for much of the matchJuventus nine points clear at the top of the Serie A table after a disappointing performance against Catania from the Italian champions.
The substitute fired home from close range, and his goal, coupled with Napoli's surprise defeat to Chievo, mean Antonio Conte's side are now clear favourites for the Serie A title.
The Serie A leaders looked to impose themselves on the game early, but only had an Andrea Barzagli long range effort to show for their early endeavours, with the defender's strike flying over the bar.
Mirko Vucinic was rested for the Champions League win over Celtic in midweek, and the break seemed to have done him good as he tested Mariano Andujar for the first time, but the goalkeeper turned his shot from distance behind for a corner.
The visitors had obviously decided to try and counter the attacking threat of Conte's side, but they almost took the lead themselves when Alejandro Gomez tried his luck from distance, but Gianluigi Buffon was equal to it despite initially spilling his effort.
Long range efforts were becoming a theme of the match, with Francesco Lodi and Leonardo Bonucci both firing wide before the home side twice went agonisingly close to breaking the deadlock.
Claudio Marchisio curled a shot wide after good interplay with Vucinic, before the Montenegro striker hit the post after capitalising on a breakdown in communication in the Catania defence.
The remainder of the half passed with little incident on the field, though Catania coach Rolando Maran was sent to the stands after arguing with the officials.
The second half continued where the first had left off, with Juventus pressing at every opportunity, and Andujar had to be at his best to deny both Bonucci and Paul Pogba in quick succession.
Pogba was slowly making his way into the match after a quiet start, and he went close again as he volleyed an effort wide from 25 yards.
Vucinic was still the biggest threat for Conte's side, but his finishing wasn't up to its usual standard, highlighted when he could only shoot wide from close range under pressure from the impressive Andujar.
Juventus rang the changes in search of a breakthrough, and one of their substitutes Alessandro Matri went close with a header as the game entered its final 10 minutes.
Giaccherini then took centre stage as he went from zero to hero. The winger was booked for diving in the last minute of normal time, but redeemed himself when he slotted home from close range after Andujar flapped at Pogba's searching cross.
Fabio Quagriella almost doubled the lead, but Andujar parried well from the Italy striker.