The utilization of polymer crystallization to manipulate the self-assembly of polymeric amphiphiles in solution is gaining increasing attention for the design of anisotropic core-shell nanoparticles and even more complex hierarchical architectures. Notably, the living-crystallization-driven self-assembly (CDSA) method, which involves seeded growth, has emerged as an ambient temperature approach for creating low-dispersity nanomaterials such as one-dimensional (1D) cylinders and two-dimensional (2D) platelets. This technique offers predictable size control and facilitates the creation of segmented structures with spatially defined compositions and functionalities, and in this process the epitaxial crystallization is regarded as the intrinsic mechanism of living CDSA. For this context, in this Viewpoint, we delineate the key aspects of the living CDSA seeded growth method, with a particular emphasis on the mechanism of seeded heteroepitaxial growth employing crystalline cores with distinct chemistries from the polymer crystallization perspective. Revealing the in-depth mechanism of heteroepitaxial crystallization enables the expansion of the design of segmented nanoparticles where the core compositions and functionalities are spatially defined. Utilizing the chemically distinct compositions and polymer crystallization strategies, the synthetic processes of 2D hollow platelets with a unique architecture are also summarized, which are of special interest for soft matter.