OBJECTIVES: The aim of this study was to comparatively evaluate the enamel remineralization potential and antibacterial efficacy of polydopamine coated chicken eggshell derived amorphous calcium phosphate (PDA -EACP) and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). MATERIALS AND METHODS: EACP was synthesized from chicken eggshells, functionalized with PDA, and then characterized using high-resolution scanning electron microscopy with energy-dispersive X-ray spectroscopy (HRSEM-EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). 120 enamel slabs were demineralized and randomly divided into 5 groups for the following therapeutic treatments: Group I- Control (no treatment); Group II - CPP-ACP; Group III- EACP; Group IV- PDA; Group V- PDA-EACP and subjected to a 28-day pH cycling regimen. The remineralization effects were assessed by measuring changes in Vickers Microhardness (VMH), analyzing surface morphology using SEM and performing elemental and chemical analysis through EDX and XRD. Antibacterial efficacy was evaluated using agar diffusion, direct contact, and biofilm inhibition assays using fluorescent staining method against Streptococcus mutans. RESULTS: Post-demineralization, VMH values dropped from 340 to 350 VHN to ~ 200-214 VHN. PDA-EACP showed the highest remineralization (330.4 ± 12.2 VHN), significantly greater than EACP (295.6 ± 10.4 VHN) and CPP-ACP (265.3 ± 9.8 VHN) (p < 0.001). EDX analysis showed Ca/P ratio increased to 2.31 ± 0.34 (EACP) and 1.69 ± 0.06 (PDA-EACP). XRD confirmed superior hydroxyapatite crystallization in PDA-EACP. PDA-EACP exhibited the largest inhibition zone (15.6 ± 1.3 mm) and highest biofilm reduction (72.6% bacterial death at 1:1 dilution). CONCLUSION: PDA-EACP enhances enamel remineralization and antibacterial activity more than CPP-ACP. CLINICAL RELEVANCE: PDA-EACP provides a biomimetic, cost-effective, and biocompatible alternative to synthetic remineralizing agents to treat early enamel lesions. Its strong adhesion potential, mineralization and antimicrobial properties could improve clinical outcomes in managing and preventing incipient carious lesions.