Barca had to be patient in an even and often cagey first half, with Juve creating some decent chances on the break but Messi did manage to break the deadlock on the stroke of half-time.
The Argentine star played a neat one-two with Luis Suarez before unleashing a shot from the edge of the box that went beyond Gianluigi Buffon and low into the corner of the Juve goal.
Messi turned provider for Barca's second as his cross was only half cleared on the stretch by Barzagli, before being picked up by Rakitic for a simple tap-in from close range.
The Barcelona talisman made sure of the result with around 20 minutes to play, as he evaded two defenders and slotted the ball home.
Juve mounted a late response and Paulo Dybala saw an effort well saved by Marc-Andre ter Stegen, but last season's runners-up had left it too late and in the end the victory looked fairly comfortable for Barcelona.