<p>Household food waste is a significant economic, social, and environmental issue in many countries. Many initiatives have been undertaken to tackle this problem, but there is a lack of research analysing their effectiveness. This study aims to assess the effectiveness of a household food waste intervention implemented by a local council in Australia. The study recruited residents from the Sydney Inner West Council area to participate in a series of workshops, an email newsletter campaign, and an online course addressing various aspects of reducing household food waste. A longitudinal analysis was performed using an online survey (<i>n</i> = 406) that measured food behaviours and self-reported food waste among participants in the intervention and control groups at three different time points. The sample mainly comprised middle-aged respondents (35–54 years), mostly women. The findings reveal that both groups reduced their food waste, although the intervention's causal effect did not differ significantly from that of the control group. Face-to-face workshops were more effective in reducing food waste than interventions that only shared information. Based on these findings, this study offers recommendations for practitioners to improve the design and delivery of future household food waste reduction interventions.</p>