The peptide-mediated functionalization of inorganic particle surfaces is demonstrated on gadolinium oxide (GdO) particles, revealing specific means to functionalize nano-or microparticles. Phage display screening is exploited to select 12mer peptides, which exhibit sequence-specific adhesion onto surfaces of GdO particles. These peptide adhesion domains are exploited to effectively decorate GdO particles with fluorescently labeled poly(ethylene oxide) (PEO), proving to result in a stable surface modification as shown by significant reduction of protein adsorption by 80%, compared to nonfunctionalized particles. Peptide adhesion and stability of the noncovalent coating are investigated by adsorption/elution experiments and Langmuir isotherms. Fluorescence microscopy, contact angle, and energy dispersive X-ray (EDX) measurements confirmed the sequence specificity of the interactions by comparing adhesion sequences with scrambled peptide sequences. Noncovalent, but specific modification of inorganic particle surfaces represents, a generic strategy to modulate functionality and function of nano- or microparticle surfaces.