In 1988, Bowlby posited that the emotional availability of psychotherapists in establishing a secure base environment is influenced by their personal relational history. Despite the acknowledged influence of the therapist’s attachment on therapeutic processes and outcomes, the therapist’s role as a secure base figure has received insufficient attention. This study delves into the connection between psychotherapists’ attachment organization and their self-perceived roles as secure base figures within clinical contexts. Additionally, we explore the mediating role of emotion regulation processes in this context. The dataset comprises self-reports from 384 psychotherapists with diverse theoretical orientations. Our analysis reveals both direct and indirect effects of psychotherapists’ attachment on the provision of a secure base. Emotion regulation, specifically through the dimension of clarity, emerges as a significant mediator in this relationship. This study offers a distinctive contribution to deepening our understanding of the relational dynamics inherent to psychotherapeutic practice. It sheds light on the nuanced relation between attachment and emotion regulation, influencing the psychotherapist’s role as a secure base figure in psychotherapy. The discussion of the results additionally emphasizes key implications for clinical practice and therapists’ training.