Internet of things (IoT) technology plays a vital role in the current technologies because IoT develops a network by integrating different kinds of objects and sensors to create the communication among objects directly without human interaction. With the presence of internet of things technology in our daily comes smart thinking and various advantages. At the same time, secure systems have been a most important concern for the protection of information systems and networks. However, adopting traditional security management systems in the internet of things leads several issues due to the limited privacy and policies like privacy standards, protocol stacks, and authentication rules. Usually, IoT devices has limited network capacities, storage, and computing processors. So they are having more chances to attacks. Data security, privacy, and reliability are three main challenges in the IoT security domain. To address the solutions for the above issues, IoT technology has to provide advanced privacy and policies in this large incoming data source. Blockchain is one of the trending technologies in the privacy management to provide the security. So this chapter is focused on the blockchain technologies which can be able to solve several IoT security issues. This review mainly focused on the state-of-the-art IoT security issues and vulnerabilities by existing review works in the IoT security domains. The taxonomy is presented about security issues in the view of communication, architecture, and applications. Also presented are the challenges of IoT security management systems. The main aim of this chapter is to describe the importance of blockchain technology in IoT security systems. Finally, it highlights the future directions of blockchain technology roles in IoT systems, which can be helpful for further improvements.