Interaction structures (IS) are reciprocal and mutual patterns of interaction between the therapist and patient, sometimes without either being aware of them. IS are mostly unique to each dyad but also can capture patterns that might be due to a particular therapy approach or clinical condition. The identification of IS in online psychodynamic settings can help clarify whether truly dynamic processes occur in virtual therapeutic relationships. The present study aimed to describe the general characteristics of the psychotherapeutic process and to identify the interaction structures in the online psychodynamic psychotherapy with an anxious patient. This was a longitudinal, systematic case study. The 24 online psychodynamic psychotherapy sessions were analysed by independent judges using the Psychotherapy Process Q-Set. Through the exploratory factor analysis of the main components, four IS were identified: (1) confident patient and encouraging therapist, (2) introspective patient and therapist fostering independence, (3) patient feeling understood and responsive/non-critical therapist, and (4) conflicted dyad exploring relationships. All patterns of interaction showed clinical validity, and pattern number (2) was positively associated with the treatment time. The study suggests that a truly psychodynamic process can be achieved in virtual settings. This kind of study denotes the characteristics of the dyad interaction and can contribute to the development of guidelines for therapeutic management attuned to the idiosyncrasies of the patients. More research on online practice is needed.