Mindfulness has become central in psychotherapy due to its benefits for patients with various mental health issues (Gu et al., 2015; Haller et al., 2021; Khoury et al., 2013). While Mindfulness-Based Interventions (MBIs) have expanded in clinical psychology, less attention has been given to their impact on therapeutic skills and processes. This scoping review, maps how mindfulness has been conceptualized and studied in clinical psychology over the last 24 years to inform an operational definition applicable to psychotherapy research. A total of 101 publications were reviewed, with most (N = 52) addressing theoretical aspects and the standardization of MBIs. Few studies have explored mindfulness as a therapist factor, and its integration into psychotherapy process research remains limited. These findings highlight the need to investigate mindfulness as an in-action skill, contributing to therapist training and research on its role in the therapeutic alliance and patient outcomes.
