Background: Early childhood caries (ECC) compromise the nutrition, growth, and quality of life in young children, and their relationship with breastfeeding practices remains disputed. Aim: To determine if prolonged breastfeeding increases the risk of dental caries in children aged under 71 months. Material and Methods: A systematic review of PubMed, Multidisciplinary Digital Publishing Institute, and Evidence-Based Dentistry, was conducted through August 2025, including observational studies, randomized trials, narrative reviews, and meta-analyses on breastfeeding and ECC. Results: Thirty-one studies involving 28,000 children were included. Exclusive breastfeeding for under six months halves ECC probability (OR 0.53–0.58), whereas breastfeeding beyond 12 months and nocturnal feeds increase probability by 60–86% (OR 2.35–7.14). Parental factors—high plaque levels, feeding-to-sleep, and skipped post-feed cleaning—strongly predict ECC (OR 8.51–75.6). Interventions combining feeding counseling with home visits or visual aids reduce ECC incidence by 22–32% (RR 0.68–0.78). Conclusions: Exclusive breastfeeding through six months is protective against ECC, but prolonged or nocturnal feeding heightens risk. Integrating structured oral health education into breastfeeding promotion is recommended.