In response to New South Wales’ target of eliminating Food Organics and Garden Organics (FOGO) waste to landfill by 2,050, this study investigates how environmental education shapes residents’ awareness and waste-sorting behaviours in multi-unit dwellings (MUDs) across Greater Western Sydney. Adopting an exploratory mixed-methods approach – integrating surveys, bin audits, interviews, and infrastructure assessments – the research reveals persistent knowledge gaps and structural constraints, particularly among culturally and linguistically diverse (CALD) households. Guided by the Action Competence Framework (ACF), the findings underscore that effective FOGO participation is not driven by infrastructure alone. Rather, it depends on inclusive, participatory, and culturally responsive education that fosters understanding, builds confidence, and strengthens a sense of shared responsibility. Intergenerational learning emerges as a critical pathway, where everyday household interactions enable behavioural shifts and help reduce contamination at the source. While limited by a small sample size (n = 33) and its exploratory scope, the study makes a meaningful contribution to environmental education scholarship by extending the application of the ACF to informal residential settings. It also offers practical insights for local governments, highlighting the need to embed community-based learning strategies that can drive sustained engagement and support long-term sustainability outcomes in high-density urban environments.