With digitalization, the connection of stakeholders in the global e-commerce supply chain has been facilitated. On the other hand, it has also introduced challenges such as increased risk of fraud and manipulation, and a lack of trust among participants who are physically separated and conducting business transactions from different locations. The involvement of intermediaries often complicates processes and raises costs. Blockchain technology addresses these issues by enabling transparent and secure transactions on a global scale, reducing the risk of fraud, eliminating unnecessary intermediaries, and strengthening trust among participants through a decentralized and immutable ledger. This paper proposes a methodology for introducing blockchain technology into the e-commerce supply chain, focusing on improving product authenticity, transparency, of business transactions, and stakeholders’ trust. The possibility of introducing blockchain in a fashion e-commerce supply chain according to the proposed methodology is shown as a proof of concept. Blockchain integration is conducted with the developed prototype of a decentralized application tailored to the fashion industry. The developed decentralized application enables conducting B2C and B2B transactions via smart contracts within the e-commerce supply chain.