The photoinduced electron transfer (PET) substitution reaction of electron‐rich aromatic nuclei with perfluoroalkyl Rf groups was carried out in water or aqueous mixtures to render substitution products resulting from replacement of aromatic H atoms with the Rf moiety in good yields (57–88 %). Some mechanistic aspects are discussed, supporting the notion of a PET reaction leading to a classical radical homolytic aromatic substitution (HAS) followed by an electron transfer (ET) and then a proton transfer (PT) sequence. A radical mechanism superimposed on a redox process is proposed to account for product formation. Evidence for the radical cation species (as an initiation event) generated from electron‐rich arenes in the presence of perfluoroalkyl halides is provided by the UV/Vis transient spectra obtained by Nanosecond Laser Flash Photolysis techniques.