Hydrogen sulfide (H2S) decomposition offers a carbon-neutral route for hydrogen production, but it remains limited by sluggish kinetics and catalyst deactivation. Here, we report an electrospinning–sulfidation strategy to engineer a confined molybdenum disulfide (MoS2) catalyst with stable edge-rich active sites. During electrospinning, confined Mo–S4²⁻ complexes are dispersed within the nanofibers, which then nucleate into MoS2 during calcination. The sulfidation stage induces exfoliation, forming highly dispersed MoS₂ domains that interact strongly with the carbon nanofibers. The prepared catalyst has a high surface area (~ 180 m2 g⁻1), abundant sulfur-vacancy edge sites, and strong support interactions, stabilized by coordinated Mo atoms. In-situ spectroscopy and ab-initio calculations reveal that these interfaces facilitate H2S dissociation, leading to a 3-fold higher intrinsic rate and improved long-term stability (> 50 h at 973 K) compared to bulk analogues. This work establishes design principles for fabricating grafted, stable, and highly dispersed sulfide catalysts.