Background: Aboriginal Australians have higher cancer mortality than non-Aboriginal Australians. Lower rates of cancer treatment among Aboriginal people can contribute to this. Aims: To investigate demographic, clinical and access factors associated with lung, breast and bowel cancer treatment for Aboriginal people compared with non-Aboriginal people in New South Wales, Australia. Methods: Population-based cohort study using linked routinely collected datasets, including all diagnoses of primary lung, breast or bowel cancer from January 2009 to June 2012. Treatment (surgery, radiotherapy or chemotherapy) within 6 months from diagnosis was measured. Access was measured using minimum distance to radiotherapy or hospital with a cancer-specific multidisciplinary team, visit to a specialist and possession of private health insurance. Logistic regression modelling was employed. Results: There were 587 Aboriginal and 34 015 non-Aboriginal people diagnosed with cancer. For lung cancer, significantly fewer Aboriginal than non-Aboriginal people received surgery (odds ratio 0.46, 95% confidence interval 0.29���0.73, P < 0.001) or any treatment (surgery, chemotherapy or radiotherapy; odds ratio 0.64, 95% confidence interval 0.47���0.88, P = 0.006) after adjusting for sex, age, disease extent and comorbidities. They were less likely to have an attendance with a surgeon (27.0%, 62/230 vs 33.3%, 2865/8597, P = 0.04) compared with non-Aboriginal people. There were no significant differences in cancer treatment for Aboriginal people compared with non-Aboriginal people for breast or bowel cancers after adjusting for patient sex, age, disease extent and comorbidities. Conclusion: Aboriginal people were significantly less likely to receive surgery for lung cancer than non-Aboriginal people and had fewer attendances with a surgeon, suggesting a need to strengthen referral pathways.