Carbon–fluorine (C–F) bonds are among the strongest and most chemically inert single bonds in organic chemistry. However, their selective cleavage has emerged as a powerful strategy for the late-stage functionalization of fluoroarenes, which serve as critical structural motifs in pharmaceuticals, agrochemicals, and advanced materials. Among transition-metal catalysts, copper provides a highly attractive, low-cost, and sustainable platform for constructing carbon–sulfur (C–S) bonds through the activation and substitution of C–F bonds in electron-deficient fluoroarenes. This review comprehensively summarizes the development of copper(I)-mediated and -catalyzed defluorinative functionalizations leading to C–S bond formation. We highlight the utility of diverse sulfur sources—including thiols, thiolates, disulfides, and thioacetates—and evaluate the critical roles of ligands, bases, solvents, and oxidants in modulating reactivity. Special attention is dedicated to the factors governing regioselectivity and the underlying mechanistic pathways, specifically distinguishing between conventional nucleophilic aromatic substitution (SNAr)) and transition-metal-assisted pathways such as oxidative addition/reductive elimination, copper–thiolate intermediates, and single-electron transfer (SET). Finally, we discuss current limitations and outline future opportunities in the field, including the catalytic activation of mono- and difluoroarenes, ligand-controlled selectivity, photocatalytic and electrochemical copper chemistry, heterogeneous catalysis, and applications in materials science.