This work reveals a facile in-situ fabricating strategy for graphene oxide/poly(ionic liquid) composites toward the effective adsorption of methyl orange in aqueous solution. This synthetic route includes the formation of novel surfactant-free ionic liquid microemulsions and the stable solubilization of graphene oxide. To characterize the designed composites, FTIR, XRD, TGA, SEM, DSC, and XPS analyses were conducted, and the adsorption isotherms/kinetics of the designed composites toward methyl orange were further investigated. Results indicated that graphene oxide/poly(ionic liquid) composites can be in-situ synthesized facilely within the surfactant-free ionic liquid microemulsions, and the network structure of composites can be adjusted effectively by altering the dosage of co-solvent. In addition, the graphene oxide/poly(ionic liquid) composites prepared in situ exhibited a remarkable adsorption performance of methyl orange. These findings indicate the great application potential of graphene oxide/poly(ionic liquid) composites in the field of cationic dye adsorption.