Highly stable graphene oxide (GO)-based multilayered ultrathin films can be covalently immobilized on solid supports through a covalent-based method. It is demonstrated that when (3-aminopropyl) trimethoxysilane (APTMS), which works as a covalent cross-linking agent, and GO nanosheets are assembled in an layer-by-layer (LBL) manner, GO nanosheets can be covalently grafted on the solid substrate successfully to produce uniform multilayered (APTMS/GO)N films over large-area surfaces. Compared with conventional noncovalent LBL films constructed by electrostatic interactions, those assembled using this covalent-based method display much higher stability and reproducibility. Upon thermal annealing-induced reduction of the covalent (APTMS/GO)N films, the obtained reduced GO (RGO) films, (APTMS/RGO)N, preserve their basic structural characteristics. It is also shown that the as-prepared covalent (APTMS/RGO)N multilayer films can be used as highly stable source/drain electrodes in organic field-effect transistors (OFETs). When the number of bilayers of the (APTMS/RGO)N film exceeds 2 (ca. 2.7 nm), the OFETs based on (APTMS/RGO)N electrodes display much better electrical performance than devices based on 40 nm Au electrodes. The covalent protocol proposed may open up new opportunities for the construction of graphene-based ultrathin films with excellent stability and reproducibility, which are desired for practical applications that require withstanding of multistep post-production processes.