Electropolymerization of the acid dye of fuchsin acid (or acid fuchsin) can produce electrochemically active films in strong acidic aqueous solutions. The electropolymerization of fuchsin acid can be enhanced by Nafion®, and polymerized fuchsin acid films are stable and show obvious electrochemical activity in acidic aqueous solutions. These films can be produced on glassy carbon, platinum, gold, and transparent semiconductor tin oxide electrodes. An electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of poly(fuchsin acid) films and the growth enhancement by Nafion®. Fuchsin acid is a molecule that has three branched monomers, and on polymerization, it forms a dendrimer. The polymer films exhibited one redox couple, and when transferred to acidic aqueous solutions at various pH, the formal potential was found to be pH dependent. The electrocatalytic reduction of epinephrine, melatonin, and 3,4-dihydroxyphenylalanine by poly(fuchsin acid) films in acidic aqueous solutions showed obvious electrocatalytic activity.