Two different soluble polymers, poly(ethylene glycol) (PEG) and poly (methacrylic acid) (PMAA), with individual functions were successfully employed in combination with a third additive, sodium dodecyl sulfate (SDS), in one system, and spherical assemblies (e.g., hollow spheres) with multiscale constructs of CaCO3 were obtained. The variation of polymer concentration drastically changed both the morphology and polymorph of the produced CaCO3 crystals due to the corresponding transformation of the micelle structure. This study suggests that noncovalent interaction and cooperation between soluble macromolecules play key roles in controlling the growth of biominerals. The results also suggest a novel and facile route toward biomimetic inorganic synthesis.