Purpose: The purposes of the present study are to describe changes over time in the prevalence of unmet supportive care needs of Indigenous Australians newly diagnosed with cancer and to identify factors associated with greater needs at diagnosis. Methods: Unmet needs were assessed by the Supportive Care Needs Assessment Tool for Indigenous People (SCNAT-IP) within 3 months and at 6 months post-diagnosis. Overall needs and specific need domains were modelled using generalized estimating equations. Associations between risk factors and moderate-high unmet needs at diagnosis were assessed using multivariable logistic regression analyses. Results: Over half (54%) of the participants (n = 82) experienced at least one moderate-high unmet need at diagnosis which reduced to 34% at 6 months post-diagnosis. This improvement mainly reflected the decrease in needs from the physical/psychological domain (p = 0.042). The median overall unmet need score and most domain scores were significantly lower at 6 months. Eighteen percent experienced multiple (5+) moderate-high unmet needs at diagnosis (60% continued to report needs at 6 months). The top unmet needs at diagnosis were money worries (27%), concerns about the worries of those close to you (16%) and worry about your illness spreading/getting worse (15%). Having a higher education and having received cancer treatment in the last 30 days were significantly associated with greater needs at diagnosis. Conclusions: While unmet needs decreased over time, some patients continued to experience moderate-high unmet needs. This study indicates that needs should be monitored throughout the patient’s journey. Coordination of support, particularly for those with multiple needs, may be important for this group.