A versatile approach is introduced for the synthesis of well-defined, biocompatible conjugates combining two-photon chromophores and hydrophilic multifunctional polymers synthesized by RAFT controlled radical polymerization. As an illustration, two different classes of conjugates carrying multiple fluorophores (based on an anthracene moiety, Anth) or photosensitizers (based on a dibromobenzene moiety, DBB) along the polymer chain were elaborated for bioimaging and photodynamic therapy (PDT) applications, respectively. In both cases, the polymer greatly improved the solubility in biorelevant media as well as the cell uptake. Anth conjugates provided high quality fluorescence microscopy images using both one- and two-photon excitation. DBB conjugates potently induced the death of cancer cells upon photoactivation.