Background: People with cancer are at higher risk of serious illness and death from COVID-19 infection. We investigated the differences in COVID-19 vaccine uptake and attitudes in people with various solid organ and hematological malignancies. Methods: An online survey of adult patients with cancer attending eight health services across four states in Australia, was conducted from June to September 2021. Demographics, cancer history and vaccination status were recorded. Only completed surveys were analysed. Variables were compared with chi-squared and multivariable analysis using logistic regression. Vaccine hesitancy was assessed using the Oxford COVID-19 Vaccine Hesitancy Scale, the Oxford Vaccine Confidence and Complacency Scale, and the Monash Disease Vaccine Acceptance Scale. T-test analysis was used to examine relationships between the scales and groups. Results: There were 2997 evaluable responses; 53.2% female, 61.8% from metropolitan areas, 27.5% with metastatic solid organ disease and 50.6% on current anti-cancer treatment. Patients with GI cancers comprised 13.5% (n = 405), compared with hematological 28.4%, breast 24.6%, genitourinary 14.1% and other cancer types 19.4%. Vaccination rates were significantly lower for respondents with GI cancers compared to other cancer types (71.6% v 79.3%; p< 0.001). Significant differences in the GI cancer population compared to all others were: more males (p < 0.001), lower level of education (p= 0.001), fewer reporting English as first language (p = 0.02) and shorter time since cancer diagnosis (p < 0.001). These remained significant after logistic regression. Among GI cancer respondents, factors associated with being vaccinated compared to unvaccinated included: older age (p < 0.001), higher education level (p = 0.03) and English as first language (p = 0.01). There was no significant difference in the scales measuring vaccine hesitancy, confidence and complacency, for the GI cancer population compared to other cancers. As expected, there were significant differences in all scales comparing vaccinated to unvaccinated respondents with GI cancers. Conclusions: In our large, contemporary survey, Australians with GI cancers report lower COVID-19 vaccine uptake compared with patients with other cancer types. We identified demographic and disease related characteristics that contribute to these differences. Interventions and targeted communication are required for people with GI cancers to maximise vaccination uptake in this medically vulnerable group.