This study explored how Technique-Centered Art Therapy (TCAT), focusing on three-dimensional perspective drawing, could induce therapeutic changes in an adolescent cancer patient who initially showed resisted affect-centered art therapy during the COVID-19 pandemic. The study employed a descriptive case study design. The participant was a 14-year-old female adolescent undergoing long-term treatment for acute lymphoblastic leukemia. Between March and August 2021, a total of 17 sessions were conducted through both online (Zoom) and face-to-face formats. The structured stepwise program incorporated tasks of cube drawing, one-point perspective, two-point perspective, and value gradation, gradually extending toward creative production. The findings indicated a decrease in avoidance and fatigue, and an increase in self-regulation and spontaneous expression. Technical mastery was associated with enhanced self-efficacy and self-esteem, while technical immersion fostered cognitive control, predictability, and emotional stability, promoting self-recovery. The results suggest that Technique-Centered Art Therapy can serve as a practical alternative for adolescent cancer patients who find direct emotional expression challenging, by reducing expressive resistance and restoring engagement and flow. Based on these findings, future studies should adopt multiple-case or mixed-method designs to validate the generalizability of effects and further investigate the relationship between technical immersion and changes in the brain’s Default Mode Network (DMN).