Nutrition knowledge is a primary factor influencing food choices and the ability to identify nutritional risk for carers of people with dementia. Acquiring nutrition knowledge helps carers monitor changes in food intake and micronutrient intake, and whether a healthy and balanced diet is being consumed. This study aimed to assess the nutrition knowledge of carers in the Australian community and their experiences with nutrition education. Using a mixed-methods approach, the nutrition knowledge of informal carers was assessed using the revised General Nutrition Knowledge Questionnaire (AUS-R-NKQ), and interviews of informal carers were used to explore the perspectives in a sub-sample. A total of 57 carers (44 females; mean age of 63.0 ± 13.1) completed the survey, and 11 carers participated in follow-up interviews. The total sample scored 22.9 (±4.57) out of 38 on the AUS-R-NKQ, suggesting basic nutrition knowledge. The interviewed carers acknowledged the importance of healthy nutrition but viewed the provision of a healthy diet for a person with dementia as challenging. In both the survey and interviews, carers reported limited use and availability of dementia-specific nutrition resources. Carers were unsatisfied with the advice and number of referrals provided to improve the nutrition of the person with dementia and desired less confusing nutrition education materials adapted to their level of knowledge. The present study highlights the need for informal carers to be supported to acquire adequate nutrition knowledge.