Slow fashion is a new movement in the textile industry, where slow production mode and more ethical business processes are highly considered. This movement is an alternative to buying fast fashion productsto achieve a sustainable pattern. The theory of planned behavior also includes attitudes, subjective norms, and perceived behavior control, which are commonly used to analyze the patterns of green attitudinal variables through other additional principles, namelythe willingness to pay a premium, consumer effectiveness, and environmental knowledge. Therefore, this study analyzed factors influencing purchase intention of slow-fashion products. In this analysis, a randomized questionnaire was implemented and distributed to 140 Generation Z people in West Java Province, Indonesia. Structural equation modelingwas also used to test the fit model and path analysis of attitudes mediating green products knowledge on the intensity of buying slow-fashion products. The results showed that the three main variables of TPB and other influential/significant expanding principles were observed, except consumers' perceived effectiveness did not affect purchase intention. The limitations also prioritized the need for more experimental loci capable of being developed at different points. Moreover, the results obtained were beneficial for both academic and managerial purposes. This proved that green product purchasing behavior analysis needs to be academically improved, specifically for slow-fashion in developing countries. Managerial suggestions also increased green knowledge of fashion products through descriptive analysis. These suggestions enhanced consumers' understanding of the effective reduction of textile waste by purchasing fashion products.