Linked with a move to Paris Saint-Germain, Neymar only needed 45 minutes at MetLife Stadium to once again show what he is capable of.
The Brazil international scored a first-half brace, a neat finish followed by a spectacular individual goal in New Jersey.
Neymar dribbled past five Juve markers before finishing for his second goal as Barca dominated in Ernesto Valverde's first game in charge.
Lionel Messi was also typically impressive, but he had to play second fiddle to Neymar before Barca played a different XI in the second half.
Juve were much-improved after the break and managed to pull a goal back through Giorgio Chiellini.
Valverde named a relatively strong Barcelona XI, which included Neymar, as Luis Suarez and off-season recruit Nelson Semedo started on the bench in their first pre-season game.
In action for the first time since their Champions League final loss, Juve handed debuts to Rodrigo Bentancur, Douglas Costa, Mattia De Sciglio and Wojciech Szczesny, although the latter trio did not start.
Barcelona made an energetic start, pushing Juve back from the outset as Neymar and Messi both squandered chances from free-kicks.
Neymar was lively down the left and he opened the scoring in the 15th minute.
The Brazil star received a pass from Messi before playing a one-two with Paco Alcacer, holding off Stephan Lichtsteiner and finishing into the top corner.
Neymar followed up the team goal with a moment of individual brilliance.
He again received a Messi pass, this time on the left side of the area, before dribbling across the box – leaving five Juve defenders in his wake and placing a finish past Gianluigi Buffon.
Neymar almost completed his hat-trick three minutes before half-time, Buffon getting down low to deny the forward after a delicate chipped pass from Messi, who then went close again with a free-kick.
Valverde named a new XI for the second half, including introducing Luis Suarez and Semedo.
Luis Suarez almost combined with Arda Turan for Barca's third before Juve, energised by the introduction of Paulo Dybala on the hour-mark, pulled a goal back.
Chiellini got between two markers to powerfully head in a Dybala corner at the back post in the 63rd minute.
Denis Suarez missed a great chance to restore Barca's two-goal lead when he blazed over and Carles Alena and Sergi Roberto also went close as the LaLiga giants saw out their win.