Piperazine-based sulfonated polybenzoxazine (PSPBz)/graphene oxide (GO) composite membranes with 1–3 wt% TiO2 nanoparticles were developed for proton‑exchange membranes (PEMs) applications. These membranes were fabricated using a solvent-casting method, followed by thermal curing to achieve stable cross‑linked three‑dimensional network structures. The successful formation and structural characteristics of the PSPBz were confirmed using FTIR and NMR spectroscopic analyses. The thermal stability and phase-transition behaviour were investigated through TGA and DSC analyses, respectively, inferred an enhanced thermal stability with a 9.45% char yield. Additionally, SEM analysis ascertained the incorporation of GO and TiO2 nanostructures within the polymer matrix. A rutile‑phase TiO2 nanoparticles were confirmed by powder x-ray diffraction analysis (PXRD). Among the membranes developed, the PSPBz/GO/TiO2 3 wt% nanocomposite membrane exhibited the highest proton transport of 0.0477 S cm−1, considerably surpassing that of the pristine PSPBz membrane. The improved proton-conducting ability is mainly credited to the optimized TiO2 filler content, which promotes the formation of interconnected proton conduction pathways and facilitates efficient proton transport through the membrane and also the PSPBz/GO/TiO2 3 wt% membrane also exhibits better physicochemical properties, including water uptake (WU), swelling ratio (SR), ion exchange capacity (IEC), and chemical stability.