Precise control over the shape and elemental composition of colloidal nanocrystals (NCs) is challenging, especially for anisotropic growth. While the most studied nanocrystal syntheses involve homogenous nucleation and growth, the solution-based approach involving heterogenous growth from ion conductive seeds has proved to be very efficient yet less explored. The static nature and superionic conductivity of the seeds enable rapid cation transport for catalysis of defect-free, phase pure NC growth. This review aims to explain the significance of ion-conductive solid seed-based synthesis from a mechanistic point of view to produce 1D and quasi-1D NCs for applications such as photocatalysis, photovoltaics, and photodetectors. We highlight the significant synthetic information reported for heterostructure and alloyed metal chalcogenide NCs synthesized via solution–solid–solid and diffusion-controlled growth based on several kinetic and thermodynamic growth parameters. We also provide a perspective on the areas that hold promise and are in need of further development.