The defeat to the top-flight returnees was Barcelona's second in the league this season through five matches after Ernesto Valverde's toothless charges slumped to a 1-0 loss at Athletic in August.
Vidal didn't wait long to put his imprint on the affair, conceding a penalty to Granada seconds after coming on.
Antoine Griezmann also played poorly, continuing a stretch with the former Atletico star failing to record a shot on target in any of Barcelona's matches away from the Camp Nou this season.
Valverde will find himself under fire for engineering Barcelona's worst performance of the campaign, a showing that pales in comparison to last year's debacle against Liverpool at Anfield.
Barcelona now sit seventh in Spain's top flight on seven points. The Catalans have now recorded two losses while conceding 12 goals, a stark contrast to last year's returns of three defeats in 38 matches and 36 goals allowed.
With the victory, Granada move to joint-top on 10 points alongside Atletico Madrid and Sevilla, with the latter holding a game in hand ahead of Real Madrid's Sunday visit to the Sanchez Pizjuan.