The multiple benefits of ‘nature’ for human health and well‐being have been documented at an increasing rate over the past 30 years. A growing body of research also demonstrates the positive well‐being benefits of nature‐connectedness. There is, however, a lack of evidence about how people's subjective nature experience relates to deliberately designed and managed urban green infrastructure (GI) with definable ‘objective’ characteristics such as vegetation type, structure and density. Our study addresses this gap. Site users (n = 1411) were invited to walk through woodland, shrub and herbaceous planting at three distinctive levels of planting structure at 31 sites throughout England, whilst participating in a self‐guided questionnaire survey assessing reactions to aesthetics, perceived plant and invertebrate biodiversity, restorative effect, nature‐connectedness and socio‐demographic characteristics. There was a significant positive relationship between perceived naturalness and planting structure. Perceived naturalness was also positively related to the perceived plant and invertebrate biodiversity value, participants’ aesthetic appreciation and the self‐reported restorative effect of the planting. A negative relationship was recorded between perceived naturalness and perceived tidiness and care. Our findings showed that participants perceived ‘naturalness’ as biodiverse, attractive and restorative, but not necessarily tidy. Perceived naturalness was also related to participants’ educational qualifications, gender and nature‐connectedness, with women and more nature‐connected participants perceiving significantly greater levels of naturalness in the planting. These findings are highly significant for policymakers and built environment professionals throughout the world aiming to design, manage and fund urban GI to achieve positive human health and biodiversity outcomes. This applies particularly under austerity approaches to managing urban green spaces where local authorities have experienced cuts in funding and must prioritise and justify GI maintenance practices and regimes.