Background: Perimenopausal women experience hormonal fluctuations that influence various physiological systems, including musculoskeletal and metabolic health. Chronic lower back pain (CLBP) is a common complaint in this population, often associated with lumbar disc degeneration. While estrogen deficiency has been implicated in spinal degeneration, vitamin D deficiency—a prevalent issue in perimenopausal women—may also contribute to musculoskeletal deterioration. Additionally, vitamin D plays a crucial role in calcium metabolism, bone turnover, and immune modulation, which are vital during perimenopause. This study aimed to evaluate the correlation between serum vitamin D levels, bone metabolism markers, and lumbar disc degeneration in perimenopausal women with CLBP. Materials and Methods: A cross-sectional study was conducted on 200 perimenopausal women aged 45–60 years presenting with CLBP. Serum vitamin D levels were measured using enzyme-linked immunosorbent assay (ELISA), alongside serum calcium, phosphorus, parathyroid hormone (PTH), and alkaline phosphatase (ALP) levels to assess bone metabolism. Estradiol (E2) levels were analyzed to determine hormonal influence on musculoskeletal health. Lumbar spine degeneration was graded using magnetic resonance imaging (MRI) and the Pfirrmann classification. Participants were categorized into three groups based on vitamin D levels: sufficient (>30 ng/mL), insufficient (10–30 ng/mL), and deficient (<10 ng/mL). Additional parameters, including bone mineral density (BMD), body mass index (BMI), smoking status, and osteoporosis prevalence, were recorded. Statistical analysis was performed using SPSS, with significance set at p < 0.05.Results: Vitamin D deficiency (<10 ng/mL) was detected in 40% of participants, while 45% had insufficient levels and only 15% had sufficient vitamin D. Severe lumbar disc degeneration (Pfirrmann Grade IV–V) was significantly more common in vitamin D-deficient women (72%) compared to those with sufficient levels (18%) (p < 0.01). Mean serum calcium and phosphorus levels were significantly lower in the vitamin D-deficient group, while PTH and ALP levels were elevated (p < 0.05). Estradiol levels showed a negative correlation with disc degeneration severity (r = -0.42, p = 0.03), highlighting the hormonal influence on spinal health. Women with osteoporosis and a high BMI (>30 kg/m²) exhibited a higher prevalence of severe disc degeneration. Chronic back pain intensity (VAS score: 7.8 ± 1.2) was significantly higher in the vitamin D-deficient group. Conclusion: Vitamin D deficiency is highly prevalent among perimenopausal women with CLBP and is associated with severe lumbar disc degeneration and altered bone metabolism. A serum vitamin D level below 10 ng/mL, along with elevated PTH and ALP, may serve as an indicator of advanced musculoskeletal deterioration. Additionally, reduced estradiol levels further contribute to degenerative changes. Early screening and targeted supplementation of vitamin D and calcium, combined with hormonal assessment, may play a crucial role in managing musculoskeletal health in perimenopausal women.