In this work, we develop a portable, sensitive waveflex biosensor that could be used for glycosylated hemoglobin A1c (HbA1c) detection. The probe consists of multimode fiber (MMF) and multicore fiber (MCF)-based W-shaped innovative sensing structures. Localized surface plasmon resonance (LSPR) is induced by modifying the optical fiber surface with gold nanoparticles. The functionalization of zinc oxide nanowires (ZnO-NWs), tungsten disulfide quantum dots (WS2-QDs), and HbA1c antibodies on the probe surface increases the specific surface area of the fiber probe and enhances the biological specificity of the sensor, respectively. Finally, the linear range, sensitivity, and limit of detection (LoD) of the sensor probe are tested, and the results are as follows: 30– $1500~\mu$ g/mL (2.7–577 mmol/mol), 0.005 nm/( $\mu$ g/mL), and $61.8~\mu$ g/mL, respectively. The repeatability, reusability, stability, selectivity, and pH test of the probe are also evaluated to showcase its sensing performance. In addition, to verify the usefulness of the sensor, HbA1c concentrations in serum samples were tested using the sensor and the D-10 Hemoglobin Testing System. The results of the sensor are consistent with those of the D-10 Hemoglobin Testing System. Therefore, the sensor can be used to detect HbA1c concentration in human serum samples.