Abstract: The urgent demand for high-performance thermal structural materials under extreme service conditions is driving the rapid development of next-generation ultra-high-temperature ceramics. High-entropy carbonitride ceramics (HECNs), through the dual-anion strategy involving carbon and nitrogen, ingeniously integrate high-entropy effects, lattice distortion, sluggish diffusion, and “cocktail” effects. This strategy overcomes the inherent limitations of single-anion high-entropy ceramics in terms of configurational entropy and composition-property design space, making HECNs a rapidly emerging research hotspot in the field of ultra-high-temperature ceramics. Under specific compositions and processing conditions, HECNs can surpass single-anion high-entropy ceramics in certain properties while offering greater composition–property tunability, demonstrating promising development prospects. This article systematically reviews the theoretical design approaches for HECNs, including the use of thermodynamic descriptors and machine learning models to predict phase stability and mechanical properties. It also summarizes diverse fabrication techniques spanning from powders to bulk materials, coatings, thin films, and novel composite systems, and highlights recent advances in mechanical properties, thermal properties, oxidation/ablation resistance, and tribological properties. Furthermore, it demonstrates that target properties can be optimized by precisely tuning the carbon-to-nitrogen ratio and cation compositions. Finally, addressing challenges related to theoretical models, processing technologies, and applications in extreme environments, this review outlines future research directions, aiming to provide valuable insights for the development and application of high-performance HECNs.

Key words: high-entropy carbonitride ceramic, theoretical design, mechanical property, thermal property, oxidation/ablation resistance, tribological property, review