Isolated theropod teeth are frequently found in geological formations and can provide valuable information for paleoecology. Here we describe an isolated theropod tooth from the Lower Cretaceous Lianmuqin Formation in Wuerho (Urho), Xinjiang, Northwestern China. The tooth has a crown height of 30.36 mm, indicating a medium-sized species. The tooth exhibits ziphodont morphology, with smooth enamel, sub-rectangular distal denticles, and a mesial carina restricted to only the apical third with dot-like denticle remnants. The combined evidence from our cladistic and discriminant analyses supports its referral to the clade Tetanurae, although a more specific classification remains elusive. However, morphological comparisons suggest it does not belong to any known theropod from the Wuerho Pterosaurian Fauna. The medium-sized theropod represented by this tooth fills a previously unrecognized ecological niche as a secondary predator in the region’s Early Cretaceous ecosystem.