This study examines the influence of Barenbliss cosmetic product design—covering aesthetic,
functional, and symbolic aspects—on customer engagement through the fulfillment of
psychological needs based on Self-Determination Theory (SDT), namely autonomy,
competence, and relatedness. Using a quantitative survey of 236 Gen Z and millennial
consumers in Yogyakarta who used Barenbliss in the past year, data were analyzed with PLS-
SEM. Results show that aesthetic design significantly affects relatedness, functional design
affects autonomy and competence, and symbolic design affects competence. Competence and relatedness fulfillment positively influence purchase, referrals, and social influence, while autonomy impacts knowledge sharing. These findings highlight the importance of product design in meeting psychological needs to enhance long-term customer engagement.