Konsep sustainable fashion, yakni pembuatan dan penggunaan produk fesyen yang mengutamakan keberlanjutan produk dan aspek lingkungan, penting untuk diterapkan karena permasalahan lingkungan yang secara signifikan diakibatkan oleh perkembangan industri fesyen. Di Indonesia, penerapan konsep ini mulai populer di sisi penjualannya, tetapi tidak di sisi pembeliannya. Sehingga diperlukan dorongan dan dukungan lebih agar masyarakat Indonesia dapat mengadopsi konsep ini dalam perilaku konsumsi produk fesyen. Di era transformasi pasar Indonesia, platform e-commerce memiliki peluang besar dalam mendorong perilaku pembelian produk sustainable fashion. Tujuan penelitian ini adalah untuk membuat model teoretis terkait faktor-faktor yang memengaruhi niat seseorang dalam membeli produk sustainable fashion melalui aplikasi e-commerce serta untuk membuat rancangan antarmuka aplikasi yang dapat mendukung perilaku tersebut. Penelitian ini dilakukan dengan pendekatan design science research yang terdiri dari: (1) pengidentifikasian masalah secara kuantitatif dan kualitatif dengan melibatkan teori NAM, TAM, dan TRA; (2) perumusan solusi dari hasil analisis data; (3) perancangan high-fidelity prototype aplikasi; (4) pendemonstrasian skenario penggunaan aplikasi; (5) evaluasi rancangan aplikasi dengan UT dan SUS; serta (6) penarikan kesimpulan dan saran penelitian. Secara singkat, penelitian ini menunjukkan bahwa perceived enjoyment, attitude, awareness of consequences, ascription of responsibility, personal norm, dan subjective norm memengaruhi intention to purchase yang mana akan memengaruhi actual purchase. Akan tetapi, perceived usefulness, perceived ease of use, dan perceived risk tidak memiliki pengaruh terhadap intention to purchase. Dari temuan dan implikasi penelitian ini, diharapkan adanya perluasan wawasan terkait perilaku pembelian produk sustainable fashion masyarakat Indonesia serta dapat merekomendasikan rancangan aplikasi e-commerce yang dapat dijadikan acuan untuk mendukung perilaku tersebut.

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The concept of sustainable fashion, namely the manufacture and use of the fashion products that prioritise product sustainability and environmental aspects, is important to implement because of the significant environmental problems caused by the development of the fashion industry. In Indonesia, the application of this concept is starting to become popular on the sales side, but not on the purchasing side. So more encouragement and support are needed so that Indonesians can adopt this concept in their fashion product consumption behaviour. In the era of Indonesian market transformation, e-commerce platforms have a great opportunity to encourage purchasing behavior for sustainable fashion products. The aim of this research is to create a theoretical model related to the factors that influence a person's intention to purchase sustainable fashion products through e-commerce applications and to create an application interface design that can support this behaviour. This research was carried out using a design science research approach consisting of: (1) identifying problems quantitatively and qualitatively involving NAM, TAM, and TRA theories; (2) formulating solutions from the results of data analysis; (3) designing high-fidelity application prototypes; (4) demonstrating the application usage scenarios; (5) evaluation of application design with UT and SUS; and (6) drawing conclusions and research suggestions. In short, this research shows that perceived enjoyment, attitude, awareness of consequences, ascription of responsibility, personal norms, and subjective norms influence intention to purchase which will influence actual purchase. However, perceived usefulness, perceived ease of use, and perceived risk have no influence on intention to purchase. From the findings and implication of this research, it is hoped that there will be an expansion of insight regarding the purchasing behaviour of sustainable fashion products among Indonesians and can recommend an e-commerce application design that can be used as a refereference to support this behaviour.