Borderline personality disorder (BPD) is a mental health condition characterized by a pervasive pattern of impulsivity, affective dysregulation, and cognitive-perceptual symptoms. Treatment of BPD remains a significant challenge to mental health clinicians. People who suffer from BPD frequently have comorbid psychiatric disorders, which makes treatment more complex. This case study describes a course of ketamine-assisted psychotherapy (KAP) to treat a patient with co-occurring BPD and depression. KAP uses the antidepressant and psychedelic effects of ketamine embedded in a psychotherapy format to utilize the concept of an inner healing intelligence within the patient and the intersubjective relationship between patient and therapist as therapeutic factors. The positive outcomes in this case study suggest that more systematic research is warranted in the use of KAP for treatment of BPD and other personality disorders.