The first electrochemically-initiated polymerization of cyclic trisulfides was developed. The reaction is safe and rapid at ambient temperature, providing sulfur-rich polymers with a well-defined sulfur rank of three. The electrochemical method is more robust than analogous anionic polymerizations, which may motivate further uptake and exploration of this polymerization technique. Insight into the mechanism was provided by DFT calculations that revealed an intriguing self-correcting mechanism that favors propagation of the target trisulfide linkage. The product poly(trisulfide)s were used in several high-value applications including thermal depolymerization for monomer recycling, gold sorption and recovery, and copper binding and precipitation from water. More generally, because the monomers are prepared directly from elemental sulfur, this is a complementary strategy for conversion of excess elemental sulfur into value-added products. Unlike inverse vulcanization, however, the electrochemical polymerization is much milder and offers better control of sulfur-rank. Future studies will focus on the scope of this method, exploring new monomers, accessing other sulfur ranks, and preparing well-defined polysulfides with higher molecular weight and improved mechanical properties.