Haloalkanes are important chemicals in synthetic chemistry and petrochemical industry, but the separation of their isomers is a big hurdle. Herein, we report a facile energy‐efficient adsorptive separation strategy using a new class of nonporous adaptive crystals based on leaning pillar6arene. Desolvated perethylated leaning pillar6arene crystals (EtLP6) with interesting nonporous character show a preference for 1‐bromoalkane isomers over 2‐bromoalkane isomers. EtLP6 is capable of separating 1‐bromopropane, 1‐bromobutane, and 1‐bromopentane from the corresponding 1:1 (v/v) mixtures of 1/2‐positional isomers with purities from 89.6 % to 96.3 % in only one adsorption cycle. The selectivity is endowed by the different host–guest binding modes and different stabilities of EtLP6 crystalloids loaded with 1‐ and 2‐positional isomers. Significantly, the guest–adsorbed assemblies are highly stable at room temperature and EtLP6 can be reused many times without any decrease in performance. The separation of haloalkane isomers is of high practical value in both synthetic chemistry and petrochemical industry. Herein, a simple‐operating and energy‐efficient separation method by using nonporous leaning towerarene crystals to separate bromoalkane isomers is provided.