Fashion and textile upcycling is currently considered a time-consuming and labour- intensive process. Since textile waste materials are not readily available as a secondary raw material, the process of sourcing pre- and post-consumer textile waste usually requires a lot of time and effort, and often results in a high inconsistency in input materials. In consequence, upcycling operations are generally difficult to scale up. In order to address this issue, this research study aims to explore the current sourcing process of secondary raw material as well as the opportunities and challenges this sourcing process implies for a B2B trading platform of secondary raw material. In order to serve the purpose of this research study, semi-structured interviews with experienced professionals from five small and medium-sized fashion and textile upcycling companies have been conducted. The empirical data collected through the semi-structured interviews was analysed using an inductive approach of qualitative content analysis. The overall findings suggest that concerning the sourcing process of post-consumer textiles for upcycling, the identified opportunities for a B2B trading platform outweigh the challenges. However, pre-consumer textile waste is often provided in the form of an already upcycled yarn from fabric or garment suppliers which gives the impression that a B2B trading platform is less relevant in this case. Nevertheless, the empirical results might have been impacted by the small sample size and the strong focus on post-consumer textiles. Therefore, more research is necessary in order to understand how SMEs working with pre-consumer textile waste source their input materials for upcycling and which opportunities and challenges this potentially different process implies for a B2B trading platform of secondary raw material.