The Matteson homologation, first developed in 1980, elongates carbon chains by insertion into a C−B bond.1 This versatile reaction traditionally requires three steps: carbanion formation, nucleophilic addition to organoboron, and a thermo- or Lewis acid-promoted boronate rearrangement. These processes often demand exacting conditions, including cryogenic temperatures and handling of air- and moisture-sensitive reagents.2,3 Here, we report a Matteson-type homologation which integrates these three transformations into a one-pot electrochemical process. This proof-of-concept approach combines electroreductive defluorination with boronate rearrangement, eliminating the need for organolithium reagents, cryogenic conditions, or specialist setups. The available trifluoromethylarenes are employed as carbenoid precursors for the first time, expanding the scope of Matteson reaction. Comprehensive mechanistic studies, including identification of key reaction intermediates, DFT calculations, and electrochemical analysis, confirm the involvement of boronate formation and rearrangement in this “e-Matteson” homologation.