The performance of dental or orthopedic implants is closely dependent on surface properties in terms of topography and chemistry. A phosphated carboxymethylcellulose containing one phosphate group for each disaccharide unit was synthesized and used to functionalize titanium oxide surfaces with the aim to improve osseointegration with the host tissue. The modified surfaces were chemically characterized by means of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The investigation of the surface topography was performed by atomic force microscopy measurements before and after the polysaccharide coating. In vitro biological tests using osteoblast-like cells demonstrated that functionalized TiO2 surfaces modulated cell response, in terms of adhesion, proliferation, and morphology. Phosphated carboxymethylcellulose promoted better cell adhesion and significantly enhanced their proliferation. The morphology of cells was polygonal and more spread on this type of modified surface. These findings suggest that the presence of a phosphate polysaccharide coating promotes osteoblast growth on the surface potentially improving biomaterial osseointegration.