Tito Vilanova's side moved top of the table with three wins from their opening three matches of the season, but required a special strike from Adriano to tilt the match in their favour as Valencia cancelled them out for large swathes of the evening with a stout effort in defence.
Brazilian midfielder Adriano picked the ball up 25 yards out from a short corner on 23 minutes to send a drive crashing beyond the Valencia keeper Diego Alves, who would have needed step ladders to keep the effort out.
That seemed to be the cue for Barca to pile on the pressure and put distance between themselves and the hardy visitors, but apart from a Pedro effort that Alves clawed out seconds after the opening goal, Valencia cut an uncompromising unit for the remainder of the match.
With a bit more luck, they could easily have departed the scene with a point even if Barca always contained the greater threat and movement in front of a home support that was relieved to hear the final whistle after a twitchy closing 20 minutes or so.
In the final analysis, Barca will be content with the three points before the international break that sees them hold a five-point lead over bitter foes Real Madrid. Real had picked up their first win of the season with a 3-0 home win over Granada earlier in the evening.
Valencia displayed their menace early in the match operating a 4-4-1-1 formation. Roberto Soldado sent a shot spinning narrowly wide of goal from the edge of the home box on 11 minutes before Diego Alves threw himself across goal to nudge a Lionel Messi header away from goal.
Cecs Fabregas somehow managed to knock a chip wide on 25 minutes from a Messi pass before doing likewise after Alexis Sanchez had played him in with a cutback on 53 minutes that the former Arsenal midfielder somehow lifted over the bar under pressure.
With Dani Alves departing carrying an injury at half-time to be replaced by Jordi Albi, the evening was not running smoothly for the home fans.
Fabregas was hooked for Andres Iniesta midway through the second period, but Barca could not find the second goal that would ease their obvious discomfort as Messi, Xavi and Iniesta were frequently crowded out by the quality and intelligence of Valencia's defending.
Valencia could and should have equalised on 88 minutes when Victor Ruiz - who had a goal disallowed when he seemed to stray narrowly offside on 59 minutes - somehow managed to head Tino Costa's corner over from five yards out when it seemed easier to hit the target as Victor Valdes grasped at fresh air.
Jonas then had Valdes scrambling backwards as an instinctive volley hurtled over the bar seconds later, but Barca had done enough to eke out the win.
Valencia have only two points after their first league defeat of the season, but will be buoyed by the nature of this narrow defeat and their 1-1 draw at Real Madrid on the opening weekend of the season.