Propane dehydrogenation (PDH) processes typically operate at low weight-hourly space velocities (WHSV) about 10 h⁻¹ to ensure catalyst stability, limiting propylene productivity to around 0.1 molC3H6·gcatalyst-1·h-1. Here, we report that controlling the formation of sub-nm PtSn alloyed clusters encapsulated in silicalite-1 affords a catalyst that can sustain high propylene productivities. At 165 h⁻¹, the catalyst achieved about 1 molC3H6·gcatalyst-1·h-1 for over 300 hours, with >99% propylene selectivity. Furthermore, the spent catalyst can be effectively regenerated using simple air calcination. Detailed characterization and computational modelling attribute the high PDH performance to the distinctive electronic structures of the Pt sites within sub-nm alloyed clusters. The dynamic structures of these sub-nm alloyed clusters likely allow these Pt sites to access a broader range of electronic and structural configurations, expanding the reaction’s accessible energy landscape and effectively breaking the longstanding trade-off between productivity and stability that constrains conventional PDH catalysts.