Slightly crumpled aminated graphene nanosheets were prepared via the mild surface modification of graphene oxide (GO) nanosheets with p-phenylenediamine at room temperature to inhibit the restacking of graphene but avoid cross-linking during the solvothermal or microwave-assisted treatments, and then the honeycomb-like flexible graphene/polyaniline (PANI) composite film electrode, PANI@rPGO, was developed by the facile vacuum filtration and reduction. Owing to the slightly crumpled PGO nanosheets with surface amino groups, the honeycomb-like PANI@rPGO composite film, with a well-defined dispersion of PANI nanorods in the graphene-based matrix and the hierarchically porous structure, possessed superior electrochemical performance as a robust electrode in flexible solid-state supercapacitors (SSCs). The symmetric SSCs based on the PANI@rPGO electrode possessed a high capacitance of 564.5 F/g and 2015.2 mF/cm2 at 0.5 A/g (2.2 mA/cm2), superior cyclic life with retentions of 104.2 and 78.5% after 2000 and 5000 cycles at 3 A/g, as well as excellent flexibility. The mild one-pot preparation and the superior electrochemical performance make the designed PANI@rPGO composite film electrode a potential candidate for high-performance flexible SSCs.