Healthy eating patterns from sustainable food systems are crucial for population and planetary health(1). Primary schools are opportune settings for teaching children about food, nutrition and sustainability(2) (FNS), though little is known about the delivery of FNS education in this sector. This study aimed to analyse current approaches to FNS education in Australian primary schools. A cross-sectional online survey (open from August 2022–October 2023) with closed- and open-ended questions collected data about (i) teacher perceptions/attributes regarding FNS education (e.g., importance, understanding, knowledge/skills, training); (ii) FNS teaching practices (e.g., frequency, teaching approaches); and (iii) factors influencing FNS education (e.g., funding, policies). Statistical analyses were conducted using STATA. Descriptive statistics were generated for all categorical data. Chi-square tests and post hoc analyses using contingency tables and adjusted standardised residuals analysed associations between frequency of FNS education and teaching approaches (cross-curricular subject vs stand-alone subjects vs both) and presence of FNS-related policies, access to funding and teacher training. Statistical significance was set at p < 0.05. Qualitative content and thematic analyses of open-ended questions were conducted using NVivo 14. Participants were 413 Australian primary school teachers recruited via social media, organisational mailing lists and departmental school listings. Most teachers reported it is extremely/very important to teach students about nutrition (83.8%), food skills (69.7%) and food sustainability (74.1%), and these topics were considered equally important to most mandatory curriculum subjects. FNS was generally taught only 1–2 times per term (29.9%) or 1–2 times per year (31.6%), and 44.1% of teachers taught this as both a stand-alone and cross-curriculum subject. Teachers reported high levels of understanding (89.3%/92.5%/78.7%) and knowledge/skills (70.5%/75.5%/62.5%) to teach students about food, nutrition and sustainability respectively. Less than a third were trained in food (22.8%), nutrition (29.5%) or sustainability (24.5%) education. Less than a third of teachers had access to funding for FNS activities (29.8%) or training (19.9%) or were from schools with policies about including FNS education in the curriculum (28.5%). There was a significant association between frequency of FNS education and teacher training, access to funding and presence of FNS curriculum policies (all p < 0.001). Teachers who were trained to teach nutrition, food skills or food sustainability were more likely to teach this as both a stand-alone and cross-curricular subject (all p < 0.05). Within open-ended responses, teachers described personal factors (e.g., workload) that influenced their FNS teaching practices, as well as factors related to students’ families (e.g., family food practices), the curriculum (e.g., overcrowding) and the school environment (e.g., time, funding, training). Strengthening FNS education in the Australian primary school sector is an important next step for public health. Researchers and policy makers should explore opportunities for training, funding and policies to prioritise FNS within the curriculum.