Purpose: Adolescent and young adult (AYA) cancer survivors (15-39 years) often struggle with their post-cancer identity. We developed an age-appropriate positive psychology group intervention with fellow AYA cancer survivors in a nature-rich environment. The aim of this study was to examine the needs and expectations of participants of this new, 1-week post-cancer identity intervention, and to evaluate their experiences to identify factors that contribute to the quality and impact of post-cancer mental health care interventions. Methods: This was a mixed-method exploratory pilot study evaluating a new, 1-week post-cancer identity intervention. The participants (n = 13) completed questionnaires at baseline measuring needs and expectations, and on the last day of the intervention and at 1-month follow-up, measuring experiences. Results: Participants' expectations to be supported in finding their post-cancer identity and receiving acknowledgment and recognition of their suffering in fellow AYAs were met. The intervention was perceived as positively contributing to post-cancer identity development (n = 11) and several aspects of well-being. Most appreciated elements of the intervention were peer support and the nature-rich environment on perceived well-being. Conclusion: The group-based positive psychology after care intervention in nature for AYA oncology was well received by participants and provided useful feedback for improvement of future editions. The intervention could offer support to AYA's in the promotion of their well-being and post-cancer identity development, but more research is needed to confirm this.