The prevalence of Type 2 Diabetes Mellitus (T2DM) and its complications continue to rise across the globe including Sri Lanka. Diabetes Self-care activities (DSCA) are promising behaviors to reduce complications and to achieve good glycaemic control. There is a lack of data regarding DSCA and its association with glycaemic control among adults with T2DM in Sri Lanka. A descriptive cross-sectional study was conducted among purposively selected adults with T2DM (n = 300) in a teaching hospital, Sri Lanka to determine the association between DSCA and glycaemic control. Apre-tested interviewer-administered questionnaire which includes socio-demographic, diabetes-related information and Summary of Diabetes Self-care activities questionnaire was used to collect data. Data were analyzed by using descriptive statistics and Chi-square test. General diet (Healthy eating plan) (OR = 3.04, 95% CI = 1.04 - 8.88, p = 0.034), Physical activities (OR = 2.26, 95% CI = 1.29 - 3.97, p = 0.004), Medication adherence (OR = 2.87, 95% CI = 1.24 - 6.64, p = 0.011) were significantly associated with HbA1c. Medication adherence was significantly associated with poor fasting blood sugar (FBS) (OR = 1.90, 95% CI = 1.07 - 3.37, p = 0.028). The findings highlight the need for health professionals to implement health education programs on diabetes self-care activities for adults with T2DM to enhance their adherence to DSCA, as well as to maintain glycemic control.