Background: Skills Training in Affective and Interpersonal Regulation (STAIR) Narrative Therapy (SNT) has shown efficacy in alleviating symptoms of posttraumatic stress disorder (PTSD) and improving emotion regulation and interpersonal skills among individuals with complex trauma, such as childhood abuse. Although this therapy is expected to be effective for patients with complex PTSD (CPTSD), no study has directly assessed diagnostic and symptom outcomes. Moreover, the potential of therapy to achieve good outcomes in non-Western countries remains unclear. Objective: This pilot study examined the feasibility, safety, and outcomes of SNT for CPTSD among women with a history of childhood abuse in a Japanese clinical setting. Methods: Ten women aged 21–54 years ( M = 29.1 years) with childhood-abuse-related ICD-11 CPTSD were enrolled in this study. The International Trauma Interview and International Trauma Questionnaire were administered to diagnose CPTSD and assess its severity. Symptoms of dissociation and depression, difficulties in emotion regulation and interpersonal relationships, quality of life, and negative cognitions were assessed pretreatment, midtreatment (after the STAIR phase), and immediately posttreatment (after the Narrative Therapy phase), in addition to 3 months after treatment. Results: Seven of the 10 participants completed the treatment. The therapists’ adherence to the therapy protocol was 96.4%, ranging from 93.6% to 100% across therapists. Serious adverse events were not observed. Among the seven completers, six at posttreatment and all at follow-up no longer met CPTSD diagnosis. Exploratory analyses using the linear mixed-effects model showed significant improvements at posttreatment and follow-up for almost all the variables. Conclusions: The results provide preliminary evidence for the feasibility and safety of SNT for CPTSD in a Japanese clinical setting. This study is the first to report the use of SNT for individuals diagnosed with ICD-11 CPTSD using reliable clinician and self-report measures. HIGHLIGHTS This study examined the feasibility and safety of STAIR Narrative Therapy for women with ICD-11 CPTSD related to childhood abuse in a Japanese clinical setting. High therapy adherence was observed. No serious adverse events occurred.