In the crystal structure of the title compound, 5-fluorocytosinium picrate, C4H5FN3O+·C6H2N3O7−, one N heteroatom of the 5-fluorocytosine (5FC) ring is protonated. The 5FC ring forms a dihedral angle of 19.97 (11)° with the ring of the picrate (PA−) anion. In the crystal, the 5FC+ cation interacts with the PA− anion through three-centre N—H...O hydrogen bonds, forming two conjoined rings having R21(6) and R12(6) motifs, and is extended by N—H...O hydrogen bonds and C—H...O interactions into a two-dimensional sheet structure lying parallel to (001). Also present in the crystal structure are weak C—F...π interactions.