The pefloxacinium cation of the title salt, C17H21FN3O3
+·C6H2N3O7
−, is composed of an essentially planar quinoline ring system [maximum deviation = 0.021 (2) Å] and a piperazine ring, which adopts a chair conformation. In the picrate anion, the two O atoms of one of the o-NO2 groups are disordered over two positions, with an occupancy ratio of 0.56 (4):0.44 (4). In the crystal structure, cations and anions are connected by intermolecular N—H⋯O, O—H⋯O, C—H⋯O and C—H⋯F hydrogen bonds, forming a three-dimensional network. In addition, π–π interactions between the pyridine rings and between the benzene rings of the anions, with centroid–centroid distances of 3.6103 (12) and 3.5298 (11) Å, respectively, are observed