A series of nanocomposite coatings was produced, comprising a hydrogel polymer, poly(2-hydroxyethyl methacrylate)/poly(ε-caprolactone) (PHEMA/PCL) matrix with nanoscale carbonated hydroxyapatite (nCHA) filler particles. The weight fraction of the filler was varied from 0 to 20% and the composites were applied as coatings onto Ti-6Al-4V substrates. The filler distribution and surface morphology were investigated by AFM, and the mechanical stability of the coatings was characterised using nanoindentation in both dry and wet conditions. The cellular response to the coatings was also examined in vitro using human osteoblast (HOB) cells. It was found that interfacial cracking occurred for composites containing greater than 10 wt.% nCHA and that 10 wt.% nCHA composite coatings appear to offer the greatest coating stability and bioactivity compared with the other composite coatings. It was concluded that the nCHA-containing PHEMA/PCL composite coatings had the potential to provide a soft, low modulus interface between metal implants and bone.