Nature-based interventions integrate nature through facilitated, structured and regular activities to co-create active therapeutic processes. The prescribing of nature-based interventions is a growing area of social prescribing informed by a developing evidence-base linking exposure and engagement with nature to improved emotional regulation and processing for both children and adults. Three core components have been identified as characterising nature-based interventions, including: nature; meaningful activity; and social interaction. There is a wealth of research highlighting the efficacy of nature-based interventions, related to the core components, in supporting short-term changes to mental wellbeing. However, there are limited follow-up studies, so there is uncertainty regarding the sustainability of benefits. This focus on the short-term has also meant that whilst the affective characteristics of nature-based interventions have been described and attributed to improvements in participants’ wellbeing, less attention has been turned to how nature-based interventions co-create these beneficial effects. As such, we recommend engaging with psychological theories of therapeutic processes to expand our understanding of the co-creation of therapeutic experiences at nature-based interventions. Specifically, how participants’ experiences can go beyond in-the-moment respite and recovery to co-create transformational experiences that have long-term effects on participants’ wellbeing. This involves shifting focus onto the influence of two key actants, facilitators and participants, who have often been neglected in research studies.