This study investigates how Jakartan customers' purchasing decisions are impacted by Uniqlo's UT Collection brand collaborations and brand perception. Collaborations have become a strategic tactic to differentiate businesses and appeal to current customers as the fast fashion market grows more competitive. This study examines the effects of Uniqlo's collaborative branding strategy on brand perception and how these factors influence consumers' purchasing decisions. Data were gathered from 125 respondents, ages 17 to 35, who had bought at least one UT Collection product, using a structured questionnaire using an explanatory study design and quantitative research methodology. The data was analyzed using Structural Equation Modeling-Partial Least Squares (SEM-PLS). This research found that both brand collaborations and brand perception significantly and positively influences customers purchase decisions. Moreover, brand collaborations also significantly and positively influence brand perceptions.