<p>Tyramine-modified hydroxyapatite (<i>w</i>Tyr–HAp) materials were synthesized through a double-decomposition route to investigate the influence of organic–inorganic interactions on the structural and adsorption properties of apatite. The formation of Tyr–HAp results from a synergistic interplay between Ca²⁺–tyramine coordination, stabilization of amorphous calcium phosphate intermediates, heterogeneous nucleation, and facet-selective growth inhibition, which collectively promote the intimate association of tyramine with the apatitic lattice. Structural and surface analyses such as X-ray diffraction (XRD), ATR-FTIR, SEM-EDX, N₂ adsorption–desorption isotherms (BET), and pH at the point of zero charge (pH_PZC) revealed that the incorporation of tyramine significantly alters crystallinity, particle morphology, and interfacial chemistry, leading to enhanced affinity toward cationic dyes. Adsorption studies using methylene blue demonstrated improved uptake capacity and faster adsorption kinetics compared to pristine HAp, highlighting the role of tyramine in modulating surface functionality and accessibility. These results underscore the potential engineered apatite’s for targeted pollutant removal and provide a mechanistic foundation for the design of hybrid bio-inspired sorbents.</p> Graphical Abstract <p></p>