Ousmane Dembele started from the loss to Paris Saint-Germain in the UEFA Champions League, with captain Lionel Messi making a landmark 506th league appearance for the Blaugrana.
A case of redemption was on the cards for the Catalans after their thumping in midweek, but Cadiz who won the reverse fixture this season made life difficult early on.
Antoine Griezmann should've handed Barca the lead before the half-hour mark following a free-flowing counter-attack, but the Frenchman blazed well off target.
Barcelona's relentless pressure paid off two minutes from the half-hour mark when Pedri drew a foul in the area to win a penalty which Messi dispatched comfortably.
A floating ball from the right by Cadiz nearly resulted in the equaliser moments later, but Ruben Sobrino couldn't get on the end of the move.
Barcelona should've gone two goals up towards 60 minutes from the far side on the left by Messi, but goalkeeper Jeremias Ledesma smothered.
A double substitution from the Catalans midway in the second half followed in Martin Braithwaite who entered for Griezmann with Miralem Pjanic introduced for Sergio Busquets.
Dembele had the visitors on the edge with a darting run towards the near post of the area a little later, but lacked the cutting edge.
Messi should've had a brace in the closing minutes from a one-two with Pedri but after carving an angle, the Argentine scooped over from close-range.
The Catalans surrendered their lead two minutes from time when Alex Fernandez converted from the spot after a transgression in the area by Clement Lenglet, as it finished all square.