Introduction: Breast carcinoma is one of the most prevalent types of carcinoma and the leading cause of death among all carcinomas. Recently, vitamin D deficiency has been reported as a risk factor for breast carcinoma. Vitamin D, as an anticarcinoma agent, prevents cellular differentiation, stimulates cell death, reduces angiogenesis, tumour progression, and metastasis. Aim: To investigate the relationship between vitamin D deficiency and the risk of breast carcinoma. Materials and Methods: An observational study was conducted at the Armed Forces Medical College, Pune, Maharashtra, India, between November 2018 and October 2020. A total of 57 cases diagnosed with breast carcinoma and 57 healthy controls were analysed. Physical and reproductive health parameters were compared, along with vitamin D status using student’s t-test and Mann-Whitney U test. Logistic regression was used to assess the risk of breast carcinoma. Results: Out of 114 women, 57 were cases and 57 were controls with a mean age of 52 vs 48 years. The mean value of serum vitamin D levels was significantly lower (19.45 vs 27.91 ng/mL, p<0.001) than controls. The percentage of serum Vitamin D deficiency was significantly higher in cases (28 (49.1%) vs 12 (21.1%), p<0.001) compared to controls. Vitamin D concentration <20 ng/mL was significantly associated with a higher risk of breast carcinoma (OR 10.8, 95% CI 3.1-37.6). Multiparity ≥3 was associated with a decreased risk of breast carcinoma (OR 2.250, 95% CI 0.599-8.447) compared to parity ≤2 (OR 3.241, 95% CI 0.916-11.466). In luminal A and triplenegative subtypes, severe vitamin D deficiency (<20 ng/mL) was observed (p=0.045) compared to other subtypes. Conclusion: The present study findings showed that women diagnosed with breast carcinoma had low vitamin D levels, which were linked to an increased risk and prognosis of breast carcinoma. Furthermore, multiparity lowers the risk of breast carcinoma.