Herein we report a new record coordination number of 24 for actinide established in the cage-like An(BH)24 (An = Th to Cm) via using relativistic quantum chemistry methods. Analysis of U(BH)n (n = 1 to 24) confirms these series of systems being as geometric minima, with the BH as a ligand located in the first shell around the uranium. However, our additional global searches reveal the lowest-energy half-cage structure for UB24, which is extended to the series of AnB24 and prevails over the competing structural isomers such as cage. The intrinsic geometric difference for AnB24 and An(BH)24 mainly arise from the B sp3 hybridization in borane inducing strong interactions between An 5f6d7s hybrid orbitals and B 2pz orbitals in An(BH)24 comparing to that of AnB24. The fundamental trend presents a valuable insight for future experimental endeavor searching for isolable complexes with high-coordination actinide and provides a new structural motif of boron clusters and nanostructures.