This study investigates the transport behavior of a chemically reacting hybrid nanofluid containing gyrotactic microorganisms over a curved oscillating surface embedded in a spatially variable porous medium. This configuration is relevant to biological and industrial systems where non-uniform porosity and oscillatory boundaries influence heat and mass transfer. The mathematical model incorporates both homogeneous and heterogeneous chemical reactions with activation energy, and accounts for thermal and solutal relaxation phenomena using the generalized CattaneoChristov flux model—going beyond classical Fourier and Fickian laws. A curvilinear coordinate transformation reduces the governing partial differential equations to a system of nonlinear ordinary differential equations, solved numerically using the Finite Difference Method with Blottner’s algorithm. The novelty of this work lies in coupling spatially variable porosity with a curved oscillating surface under bioconvection and dual chemical reaction mechanisms, which has not been previously addressed. These f indings provide new insights into heat and mass transport in complex porous structures and can guide the design of advanced systems in biomedical engineering, environmental remediation, and nanofluid-based thermal management technologies. The analysis reveals that increasing nanoparticle concentrations enhances thermal transport and microbial activity near the surface due to increased thermal conductivity and fluid–structure in teractions. Notably, the combined effects of variable porosity and oscillatory curvature significantly modify local transport rates and lead to distinctive periodic behaviors in temperature and species gradients, underscoring the crucial role of non-uniform porous media and unsteady boundary dynamics in controlling bioconvective hybrid nanofluid systems.