<p>Motivated by emerging bioinspired nanoscale coating operations, a theoretical and numerical investigation of hydromagnetic gyrotactic bioconvective heat and mass transport characteristics in ternary Williamson hybrid nanofluid (water–Cu + CuO + Al₂O₃ nanoparticles) flow on a revolving cylinder adjacent to a porous medium is presented. To simulate thermal relaxation effects, a non-Fourier Cattaneo–Christov heat flux model is deployed. Rosseland’s model is utilized for radiative flux. For the porous medium, inertial (Forchheimer) drag is included in the model. First-order destructive chemical reaction is addressed. The governing partial differential equations are transformed into ordinary differential equations using appropriate similarity transformations. The bvp4c package in MATLAB is used to solve the system of ordinary differential equations with appropriate boundary conditions.s Graphical visualization of all key transport characteristics is included, i.e. radial velocity, axial velocity, temperature, species concentration and motile microorganism density number are plotted for variation in key control parameters, i.e. thermal radiation flux, Forchheimer quadratic inertial porous drag, Weissenberg viscoelastic, magnetic field, Péclet, chemical reaction, heat source, thermal relaxation (non-Fourier), activation energy and bioconvection Lewis numbers. Moreover, the skin friction, Nusselt number, Sherwood number and motile microorganism density gradient (microorganism mass transfer rate to the cylinder surface) are computed using response surface methodology (RSM). Verification with the previous studies neglecting Forchheimer drag and ternary nanoparticle effects is included. It is found that an increment in bioconvection Rayleigh number supresses axial and radial velocities whereas greater Weissenberg number enhances axial velocity. With increasing thermal relaxation parameter, temperature is depleted indicating that the classical Fourier heat conduction model overpredicts temperatures. With a decreasing Peclet number, the density number of gyrotactic microorganisms is elevated. Stronger chemical reaction suppresses species concentration whereas increasing activation energy elevates it and species boundary layer thickness. When the adjusted R-squared and R-squared for the motile microorganism density number are added together, the result is 97.71%. The simulations are relevant to emerging hybrid bioconvection nanofluid coating systems which have embedded functionality and can combine microorganisms and nanoparticles features to produce optimized performance.</p>