Nucleophilic attack on carbon-based electrophiles is a central reactivity paradigm in chemistry and biology. The steric and electronic properties of the electrophile dictate its reactivity with different nucleophiles of interest, allowing the opportunity to fine-tune electrophiles for use as coupling partners in multistep organic synthesis or for covalent modification of proteins in drug discovery. Reactions that directly transform inexpensive chemical feedstocks into versatile carbon electrophiles would therefore be highly enabling. Herein, we report the catalytic, regioselective oxidative cyanation of conjugated and nonconjugated alkenes using a homogeneous copper catalyst and a bystanding N-F oxidant to furnish branched alkenyl nitriles that are difficult to prepare using existing methods. We show that the alkenyl nitrile products serve as electrophilic reaction partners for both organic synthesis and the chemical proteomic discovery of covalent protein ligands.