After a cagey first half where the visitors had the best chances, Messi gave the hosts the lead on the stroke of half-time, before a second-half goal from Ivan Rakitic and second from the Argentine completed the scoring.
Visitors enjoy bright opening
Max Allegri's stitched-up side were keen to stamp their authority on their Group D rivals, and threatened Marc-Andre ter Stegen in the Barca goal on three occasions in the opening quarter of an hour, including tipping wide full-back Mattia De Sciglio's long-range effort - despite referee Damir Skomina's insistence the German had not got a hand to the ball.
Not be outdone themselves, Ernesto Valverde's men then brought about a riposte of their own in the 20th minute. After Blaise Matuidi felled Andrés Iniesta on the edge of the box, Lionel Messi's initial shot was blocked from the free-kick, before Luis Suárez's rebound effort forced Gianluigi Buffon to palm the Uruguayan's rasping drive over the bar.
The home side were enjoying the lions share of possession but had only shied at the Juve boughs twice, whilst the Bianconeri themselves had four efforts on target in what was panning out to be a cautious opening period, as the men in black and white thwarted the trickery and pace of Barcelona's front three.
Messi conjures opener
On the rare occasions they did, a mistake from Andrea Barzagli saw the ball drop to Ousmane Démbéle, but as the Frenchman bore down on goal, Alex Sandro slid back to made a last-ditch challenge.
Just as a goal-less half appeared inevitable, Messi lit the blue touch paper on the stroke of half-time. Given a free run in midfield, the Argentine scampered forward and exchanged passes with Suarez on edge of the area. Messi then swivelled, and jinked his way majestically into space, then slipping a shot past Buffon and into the bottom-right hand corner of the net.
Barca led out of nowhere, with the Italians having no time to bounce back, as the referee's whistle blew for the break.
Rakitic doubles advantage
Buoyed by their late first half goal, the hosts continued where they left off after the break. Buffon again denied Barcelona a second from Suarez's pile-driven shot, which forced the veteran into a full-body save, with the ball ricocheting inches wide of the post.
It was only short-term survival however for Allegri's side. Again Messi was the architect. The diminutive forward escaped down the right wing and after his shot was blocked by Buffon, substitute Stefano Sturaro could only clear the ball as far as Ivan Rakitic, with the Croatian side-footing into an empty net from 12 yards out.
Maestro adds a third
Juventus had folded and were beginning to look ragged. With Messi having failed to score past Buffon before this every evening at Camp Nou, the 30 year-old then added a third - his second.
Just like every other his previous 95 goals in Europe, the Argentine almost single-handedly unlocked the Old Lady's defence for his 96th. Swerving and weaving once more, Messi checked inside and then unleashed a left-footed drive past the helpless Buffon to make the scoreline a resounding 3-0.
A late rally from the Italians saw ter Stegen forced into a smart save from Paulo Dybala's 20-yard effort, with Gerard Piqué also making a goal-line clearance.
Their efforts were in vain however, as Barcelona eased to a comfortable opening win in Group D.
Next up for La Blaugrana is a trip to Portugal to play Sporting Lisbon, whilst Juventus will look to bounce back as they host Olympiacos at the end of the month.