Strong metal-support interactions (SMSIs), one of the core concepts in the field of catalysis, have a substantial influence on catalytic performance, especially stability. Conventional view holds that only reducible metal-oxide supports could induce a SMSI encapsulation state upon high-temperature treatments. Herein, we demonstrate a high-temperature SMSI between platinum and sulfur-doped carbon (S-C) supports, featuring charge transfer, suppression of H₂/CO adsorption, and support of encapsulation. We find that the strong chemical interaction between platinum and sulfur atoms greatly suppresses platinum sintering at moderate temperatures of 300°C–700°C, along with the subsequent formation of SMSI encapsulation structures at high temperatures of 900°C–1,100°C. The high-temperature SMSI endowed the Pt/S-C catalysts with outstanding sintering resistance up to 1,100°C and enhanced electrocatalytic oxygen-reduction reaction (ORR) durability in H₂–air proton-exchange membrane fuel cells (PEMFCs).