Food, nutrition and sustainability (FNS) education in primary school can promote dietary patterns that support health and sustainability(1). However, little is known about how FNS is taught in primary school classrooms outside of time-limited interventions. This exploratory, transnational study aimed to address this gap by analysing current FNS education practices in primary schools in Australia, Sweden and the UK. A cross-sectional online survey (Aug 2022-Nov 2024) collected quantitative data about FNS education practices (frequency, teaching approach, teaching activities, information sources) and influencing factors (funding, policies, barriers). Open-ended questions were included to capture insights about FNS education deemed important by teachers. Relationships between quantitative survey outcomes and country were analysed using logistic regression models (statistical significance = p<0.05). Responses to open-ended questions were analysed using Braun and Clarke’s six-step approach to inductive thematic analysis. Respondents were 1246 teachers from Australia (33.2%), Sweden (33.6%) and the UK (33.2%). 29.8% of teachers reported FNS was taught frequently (≥once a week or once a fortnight), and teaching frequency was higher in Sweden than Australia (p=0.012) or the UK (p<0.0005). Most teachers (84.4%) used a cross-curricular approach to teach FNS and this was more likely in Sweden (p=0.005) and the UK (p=0.012) than Australia. Videos (78.9%) and real food/food labels (72.4%) were commonly used for FNS education. Teachers sourced FNS education materials from teacher-specific websites (62.4%), and more frequently created their own resources (47.5%) than using information from government departments (44.1%) or experts (8.4%). Only 29.3% of teachers had funding for FNS activities and 16.5% had funding for training in FNS education. Swedish teachers were most likely to have funding for FNS activities, whilst UK teachers were least likely to have funding for FNS training (p<0.05). Less than half of teachers (43%) were from schools with policies about teaching FNS in the curriculum, and policies were least likely in Australian schools (p<0.0005). Only 12.4% of teachers reported not experiencing barriers to teaching FNS. These teachers were most likely to be from Sweden (p<0.01). The following five themes were constructed from thematic analysis: (i) Teachers perceive FNS education as important for students; (ii) Tensions exist in perceived responsibilities and priorities for FNS education; (iii) FNS education must be sensitive to the varying needs of children and families; (iv) FNS practices vary across schools; and (v) School-based FNS practices are influenced by curriculum factors, physical school infrastructure, school and teacher circumstances, and school environment factors (time, funding, resources, support). This analysis explored FNS education practices and perceptions of teachers in Australia, Sweden and the UK and identified novel, transnational differences. Findings can be used by school stakeholders, governments and researchers to understand and strengthen the position of FNS education in primary school settings.