Purpose: The study aims to assess the implementation of an intervention program that combines nature-based solutions with an environmental citizenship pedagogical approach for pre-service teachers. The research questions revolve around the educational potentials and challenges of this intervention. To our knowledge, no previous studies resorted to this combination to organize courses for initial teacher training. Design/methodology/approach: For this qualitative and interpretative case study, data was obtained through focus groups. 30 pre-service teachers of the Basic Education Course (training kindergarten and primary school teachers) in Portugal participated in the intervention. The transcripts of the focus groups' content were subjected to categorical qualitative content analysis. Findings: According to the participants, the implemented approach contributed to the development of a better understanding of the complexity of the environmental issues addressed, and of critical thinking skills. The pre-service teachers recognized the educational potential of nature-based solutions in the promotion of their environmental citizenship and activist competences and of the pedagogical knowledge necessary for its implementation.