Background: Diabetes Mellitus is a long-term metabolic disorder with increasing prevalence in India, impacting more than 101 million people according to the ICMR-INDIAB study (2023). Insulin therapy is important for glycemic control, especially in poorly controlled diabetes, but its efficacy relies on correct administration methods and compliance. The current study seeks to evaluate the knowledge, attitude, and practice (KAP) of insulin administration among diabetic patients in a tertiary care facility. Methods: A six-month cross-sectional study was carried out on 176 insulin-treated diabetic patients in both inpatient and outpatient departments. The data were collected through a structured questionnaire that measured KAP concerning the use of insulin. Statistical analysis was carried out using SPSS software with descriptive statistics having a 5% level of significance and 95% confidence interval. Results: Results indicated pervasive knowledge gaps between patients and appropriate insulin administration practices, including inappropriate injection methods and misconceptions on its effects. Although the majority of patients had accurate answers regarding insulin storage techniques, a sizable percentage of patients showed improper site repetition and failure to monitor blood glucose levels properly. Stigma and myths associated with insulin dependency were prevalent and impacted compliance. Conclusion: This research highlights the necessity of organized educational interventions to promote patient awareness and compliance with insulin therapy. Enhancing the role of healthcare professionals in patient education and incorporating digital health approaches may enhance insulin administration practices, resulting in improved glycemic control and diabetes management.