Inorganic composite nanocrystals have been widely investigated due to their novel properties and potential applications. However, to date, more effort is needed to suppress the homogeneous nucleation and self–growth of the second–component nanocrystals. In our work, we have introduced Bi³⁺ ions which can react with the CdS mother nanocrystals (NCs) during the dissolution processes of the mother NCs. Subsequently, the nanocrystals which recrystallize on the surfaces of the CdS mother nanocrystals are Bi₂S₃ nanocrystals rather than the mother ones due to the lower solubility of Bi₂S₃. Therefore, it is effective to avoid separation between the CdS mother nanocrystals and the second–component Bi₂S₃ nanocrystals. During this dissolution–recrystallization process, the growth regime can be facilely controlled from the thermodynamic control to the kinetic domination through adding more Bi³⁺ ions or changing the heating method from an oil bath to a microwave field. Consequently, the obtained CdS–Bi₂S₃ composite nanostructures can evolve from core–shell to tangentially–bonded structures in the oil bath, while tangentially–bonded CdS–Bi₂S₃ composite NCs and nest–shaped Bi₂S₃ NCs can be achieved in the microwave field.