We present a theoretical investigation of the structural, electronic and optical properties of few layer graphene/TiO2 composites involving either single or bilayer graphene and the (101) surface of TiO2 anatase, in view of the importance of carbonaceous materials such as graphene to enhance solar light-driven photocatalytic activity of TiO2. Calculations have been performed by combining periodic DFT calculations to TD-DFT carried out on finite clusters extracted from the periodic structures and embedded in an array of point charges devised to reproduce the periodic electrostatic environment. Although van der Waals interactions dominate the graphene/TiO2 interaction, TiO2 properties are significantly affected by its combination with graphene in the composite materials. In particular, we found that such materials present favorable key features for photocatalysis applications, with high charge carriers mobilities, an increase of the absorption in the visible range together with a red-shift of the photoresponse of TiO2. These results confirm that graphene can enhance solar light-driven photocatalytic activity of TiO2, especially when few layer graphene-based composites are considered. Furthermore, the proposed computational approach appears as a reliable and effective tool to model both the electronic and the optical properties of heterostructures at low computational cost. Display omitted •A reliable and effective computational protocol is proposed to model composites.•Gr-based composites offer better properties than TiO2 for photocatalysis.•Few layer Gr-based composites offer better properties than single layer ones.