A biosensor for bovine serum albumin (BSA) detection by graphene oxide (GO) functionalized micro-taped long-period fiber grating (GMLPG) was demonstrated. The amide bond connected between the GO and BSA enabled the BSA to attach onto the fiber surface, which changed the effective refractive index of the cladding mode and characterized the concentration of the BSA. This real-time monitoring system demonstrated a sensing sensitivity of 1.263 nm/(mg/mL) and a detection limit of 0.043 mg/mL. Moreover, it illustrated superior measurement performance of higher sensitivity in the presence of glucose and urea as the interference, which showed static sensitivities of ~1.476 nm/(mg/mL) and 1.504 nm/(mg/mL), respectively. The proposed GMLPG demonstrated a great potential for being employed as a sensor for biomedical and biochemical applications.