The aim of the current study was to examine whether a combined mindfulness app and nature intervention had stronger short- and middle-term effects on mindfulness, life satisfaction, mental health, and stress than a mindfulness app-only and a nature-only intervention. In a randomized controlled trial, 89 university students were assigned to a mindfulness app-only group (n = 30), a nature-only group (n = 30), or a combination group (n = 29). The interventions consisted of 7-week mindfulness-based or nature programs. The outcomes were measured at pre- and postintervention, and at 7 weeks postintervention. Results showed that the combined group did not demonstrate better outcomes than the single interventions over short and medium term. All intervention groups improved in mindfulness, life satisfaction, and stress from preintervention to postintervention and follow-up. Thus, using a mindfulness app in a natural setting does not provide additional benefits compared to being in the nature.