Background: Low concentrations of vitamin D are considered one of the risk factors for hip fracture and are associated with worse outcomes. The purpose of this retrospective study was to compare vitamin D deficient group and vitamin D sufficient group and assess the association preoperative vitamin D deficiency and postoperative walking ability after hip fracture surgery. Methods: Between January 2014 and January 2020, 1,029 elderly patients with hip fracture (243 in men and 785 in women) were measured preoperative serum 25-hydroxy-vitamin D3 levels. Among 1,029 elderly patients, 702 patients were classified as Vitamin D deficient group (<20 ng/mL). Outcome parameters for functional recovery were the length of the hospital stay and KOVAL score, and those for complications were delirium, pneumonia, and thromboembolism. Results: The mean length of the hospital stay in the vitamin D deficient group was significantly longer than in the vitamin D sufficient group (27.7±17.8 vs. 2.9±11.8 days; odds ratio [OR], 1.03; 95% confidence interval [CI], 1.02-1.05; P=0.001). The mean postoperative KOVAL score in the deficient group was significantly higher than in the sufficient group (4.0±2.1 vs. 3.1±1.9 days; OR, 1.21; 95% CI, 1.11-1.32; P=0.001). Vitamin D deficiency was significantly associated with a higher risk of delirium and pneumonia in deficiency group. Conclusions Preoperative vitamin D deficiency in hip fractures patients was associated with prolonged duration of hospital stay and decrease of postoperative ambulatory status, and may increase the risk of delirium and pneumonia. Therefore, it is necessary to evaluate the preoperative vitamin D level and recommend vitamin D supplementation in elderly patients with a high probability of hip fracture.