The 20-minute neighbourhood (20MN) concept aims to enable residents to meet daily needs using resources within a 20-minute trip from home noting that there is no single definition of what services and amenities are required for daily needs nor what modes of transport constitute a 20 minute trip. Whether 20MNs promote better health and whether associations differ by socioeconomic status (SES) is unknown. Using cross-sectional data from adults randomly sampled in 2018-19 from Melbourne or Adelaide, Australia, we examined whether associations between neighbourhood type (20MN/non-20MN) and diet, physical activity or self-rated health vary according to individual-or area-level SES. We found no consistent patterns of interactions. The results do not consistently support the often assumed belief that 20MNs support more healthful behaviour and that these relationships vary by SES.