A facile strategy for the preparation of meso-terakis(4-methoxyl-3-sulfonatophenyl) porphyrin (T(4-Mop)PS₄)-graphene hybrid nanosheets (TGHNs) was demonstrated for the first time, which combines the features of both graphene (high conductivity and large specific surface area) and porphyrins (photochemical electron-transfer ability and excellent electrochemical activity). The as-obtained TGHNs were characterized by UV-vis spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy, transmission electron microscopy and cyclic voltammetry, which confirmed that the porphyrin had been effectively functionalized on the surface of graphene. Combined with the high affinity and specificity of an aptamer, a simple, rapid, sensitive and label-free electrochemical aptasensor was successfully fabricated for adenosine triphosphate (ATP) detection. The proposed TGHN-based aptasensor achieved the direct electron transfer of porphyrin and showed good affinity and specificity towards ATP, which avoided interference such as the introduction of labeled-substances and the [Fe(CN)₆]^3−/4− probe. The preferable linear range for ATP was from 2.2 nM to 1.3 μM (R = 0.9982) with a detection limit of 0.7 nM.