Blockchain technology is a promising technology that attracts popularity among researchers. However, it was first introduced with digital currencies in particular Bitcoin, but nowadays it is also known as one of the most frequently used techniques for securing networks. This systematic review research identifies studies that use blockchain for their security challenges. In addition, different fields in blockchain usage, blockchain categorization type, consensus mechanism, smart contract usage, and integration with other software-based algorithm is also investigated. Our results maintain that the internet of things (IoT) is the main field that blockchain is used to provide security.