For orthopedic and dental implants, the ultimate goal is to obtain a life-long secure anchoring of the implant in the native surrounding bone. To this end, nanoscale calcium phosphate (CaP) and collagen-CaP (col-CaP) composite coatings have been successfully deposited using the electrospray deposition (ESD) technique. In order to study to what extent the thickness of these coatings can be reduced without losing coating osteogenic properties, we have characterized the mechanical and biological coating properties using tape tests (ASTM D-3359) and in vitro cell culture experiments, respectively. Co-deposition of collagen significantly improved coating adhesive and cohesive strength, resulting in a remarkably high coating retention of up to 97% for coating thicknesses below 100 nm. In vitro cell culture experiments showed that electrosprayed CaP and col-CaP composite coatings enhanced osteoblast differentiation, leading to improved mineral deposition. This effect was most pronounced upon co-deposition of collagen with CaP, and these coatings displayed osteogenic effects even for a coating thickness of below 100 nm.