Nature employs specialized macromolecules to produce highly complex structures and understanding the role of these macromolecules allows us to develop novel materials with interesting properties. Herein, we report the role of modified conjugated polymers in the nucleation, growth, and morphology of calcium carbonate (CaCO3) crystals. In situ incorporation of sulfonated poly (p -phenylene) (s(PPP)) into a highly oriented calcium carbonate matrix is investigated along with the synthesis and patterning of luminescent CaCO3-PPP hybrid materials. Functionalized PPP with polar and nonpolar groups are used as additives in the mineralization medium. The polymer (PI) with polar groups give iso-oriented calcite crystals, whereas PPP with an additional alkyl chain (P2) results in vaterite crystals. The crystallization mechanism can be explained based on self-assembly and aggregation of polymers in an aqueous environment. Such light-emitting hybrid composites with tunable optical properties are excellent candidates for optoelectronics and biological applications.