The development of a visible-light-mediated biocompatible reaction under ambient aqueous conditions using a reactive traceless warhead is an unmet need for the modification of biomolecules with exquisite spatiotemporal control. Here we disclose bench-stable amino-acid-derived oxamic acid as a carbamoyl radical progenitor for the three-component vicinal carbamoylative fluorination of styrene derivatives as well as unactivated alkenes under visible light irradiation in aqueous or buffer medium, offering a unique opportunity for N-terminal modification of amino acids, peptides and biomolecules.