Arylacetic acids were used as sources of benzyl radicals under tetrabutylammonium decatungstate photocatalyzed conditions for the benzylation of electron-poor olefins. The reaction proceeds smoothly in a mixed aqueous medium (MeCN/H2O 2/1) in the presence of NaHCO3, NaClO4, and an electron transfer agent (biphenyl). The reaction tolerates a wide variety of functional groups on the aromatic ring (whether electron donating or electron withdrawing) and can be extended to heteroaromatic analogues. The olefins have the double role of radical trap and electron acceptor. The present approach can also be extended to arylpropionic acids (including the nonsteroidal anti-inflammatory drugs ibuprofen and flurbiprofen), as well as mandelic acid derivatives.