In recent years, supply chain processes have been improved through digitalization. However, digital data is sometimes unsynchronized and untrustworthy. Many blockchain applications have been developed in different supply chain industries to solve the issue based on the features of blockchain, such as tamper-proof, immutability, and traceability. The text focuses on a specific supply chain, the maritime supply chain, due to its significant position in global trade. The text aims to explore some blockchain applications in the field, compare them, and discuss them from different aspects. The text begins with the basic idea of blockchain and its evolution, followed by the basic knowledge of supply chain and maritime supply chain. By delving deeper into these topics, the text reinterprets the concept of blockchain 4.0, proposes a framework to explain the bottlenecks of digitalization in the field, and claims that blockchain can break the bottlenecks. Subsequently, the text discusses the applications from the aspect of blockchain 4.0. The advantages and disadvantages of each application’s design are shown, and suggestions to reach blockchain 4.0 are provided. Researchers and application builders can refer to the text to discover research topics and develop successful blockchain applications. The ecosystem will then become more and more efficient.