<p>Efficient hydrogenation of branched unsaturated fatty acids is crucial for the production of highly stable isostearic acid. In this study, a series of porous carbon-supported nickel-based catalysts were rationally designed and precisely prepared using metal–organic frameworks (MOFs)-derived strategies, and the regulatory effects of rare-earth promoters on catalytic performance were systematically investigated. Experimental results demonstrated that the Ni–La₂O₃@C catalyst with La₂O₃ as the optimal promoter exhibited excellent hydrogenation activity under optimized conditions, achieving a conversion of 78.9%, significantly outperforming commercial Ni/SiO₂ (46.4%) and Ni/C (70.5%) catalysts. Furthermore, this catalyst showed remarkable chemoselectivity, effectively suppressing decarboxylation side reactions and maintaining a stable acid value of the product. Combined structural characterization and density functional theory (DFT) calculations revealed that the unique interfacial effect (derived from strong metal–support interaction and interfacial electronic modulation) substantially reduced the dissociation energy barrier of hydrogen molecules (0.07 eV) and enhanced the capture and activation of C=C bonds in the substrate. This work not only provides an efficient catalytic material for the deep processing of complex lipid feedstocks but also offers valuable insights into the design of high-performance metal catalysts through interfacial engineering. The Ni–La₂O₃@C catalyst exhibits high activity and selectivity under mild conditions and is promising to replace noble metals in the industrial production of isostearic acid.</p> Graphical Abstract <p></p>