Objective This study aimed to examine the association between performance of self‐care activities and patient or disease factors as well as patient activation levels in patients with diabetes and chronic kidney disease (CKD) in Australia. Methods A cross‐sectional study was conducted among adults with diabetes and CKD (eGFR <60 mL/min/1.73m2) who were recruited from renal and diabetes clinics of four tertiary hospitals in Australia. Demographic and clinical data were collected, as well as responses to the Patient Activation Measure (PAM) and the Summary of Diabetes Self‐Care Activities (SDSCA) scale. Regression analyses were performed to determine the relationship between activation and performance of self‐care activities. Results A total of 317 patients (70% men) with a mean age of 66.9 (SD=11.0) years participated. The mean (SD) PAM and composite SDSCA scores were 57.6 (15.5) % (range 0‐100) and 37.3 (11.2) (range 0‐70), respectively. Younger age, being male, advanced stages of CKD and shorter duration of diabetes were associated with lower scores in one or more self‐care components. Patient activation was positively associated with the composite SDSCA score, and in particular the domains of general diet and blood sugar checking (P<.05), but not specific diet, exercising and foot checking. Conclusion In people with diabetes and CKD, a high level of patient activation was positively associated with a higher overall level of self‐care. Our results identify subgroups of people who may benefit from tailored interventions to further improve their health outcomes. Further prospective studies are warranted to confirm present findings.