Strong interaction between Pt nanoparticles and graphitic carbon in carbon-based and oxide–carbon composite substrates is demonstrated using electrochemical CO stripping experiments. A correlation between the in-plane crystallite size of the carbon supports and the oxidation charge of CO stripping wave was made. It appears that π-system of graphitized carbon anchors platinum particles in a way that strongly modifies the electronic properties of the Pt valence band. The effects of graphitized carbon on platinum are even observable on TiO2–carbon composite-supported Pt, where a well-known strong metal–support interaction between Pt and TiO2 is already present, demonstrating the significant extent of the interaction between Pt and graphite. Finally, a preliminary proof of the role played by the interfacial Pt–Ti nanoalloy on oxide–carbon composite is given.