Ultrafine nanoparticles (NPs) have attracted extensive research interest, especially in heterogeneous catalysis. However, the inherent sintering propensity of NPs has been a major obstacle to their catalytic stability. Here we report an isolation strategy to preserve highly dispersed ultrafine NPs under extremely harsh conditions. Oxide nano-islands were grafted between the catalyst support and metal NPs, serving as a general approach by following a charge attraction principle. Specifically, LaO