Purpose: The objective of this study is to comprehensively analyze the risk factors associated with deep vein thrombosis (DVT) complications after percutaneous coronary intervention (PCI) in elderly patients. Methods: A retrospective case-control study was conducted by analyzing the data of 101 elderly patients who underwent PCI. On the basis of the occurrence of postoperative DVT, the patients were divided into non-DVT (n = 57) and DVT (n = 44) groups. Baseline characteristics, procedural details, laboratory indicators, medication use, postprocedural complications, length of hospital stay, and rehospitalization were assessed. Results: Procedural characteristics showed lengthened procedural time (45.62 ± 7.81 vs. 42.17 ± 8.43 min, t = 2.105, p = 0.038) and increased contrast volume (161.05 ± 27.56 vs. 150.14 ± 25.67 mL, t = 2.051, p = 0.043) in the DVT group. Significant differences were observed in hemoglobin (13.92 ± 1.58 g/dL vs. 13.18 ± 1.76 g/dL, t = 2.221, p = 0.029) and serum albumin levels (4.33 ± 0.38 g/dL vs. 4.09 ± 0.42 g/dL, t = 3.006, p = 0.034) between the two groups. Moreover, compared with the non-DVT group, the DVT group had longer hospital stays (6.41 ± 2.05 days vs. 5.32 ± 1.76 days, t = 2.872, p = 0.005) and increased rehospitalization rates (27.27% vs. 10.53%, t = 4.755, p = 0.029). Correlation and logistic regression analyses identified several statistically significant associations between the risk factors and complications of DVT in elderly patients with PCI. Conclusion: The present study provides novel insights into the multifaceted nature of DVT after PCI in elderly patients and emphasizes the substantial effects of DVT on clinical outcomes. The findings underscore the need for comprehensive risk assessment, vigilant monitoring, and proactive management of DVT in this patient population to optimize patient outcomes after PCI. Future research should focus on developing targeted interventions and risk stratification tools tailored to the unique needs of elderly patients with PCI to improve clinical treatment.