The Industrial Internet of Things (IIoT) stands at the forefront of Industry 4.0, the latest industrial revolution marked by the infusion of digital technologies into industrial operations. This seamless integration serves as a catalyst for profound transformations in business practices, fostering innovation, efficiency, and heightened productivity. IIoT serves as a cornerstone in this digital evolution, alongside other transformative technologies such as big data, Augmented Reality/Virtual Reality (AR/VR), and blockchain. This chapter offers a comprehensive exploration of the pivotal role played by IIoT within Industry 4.0. It delves into the core elements of IIoT while also examining how it synergizes with big data, AR/VR, and blockchain. Real-world instances underscore the practical applications of these technologies across diverse industries, illuminating their contributions to the development of intelligent factories. Furthermore, this chapter delves into the advantages and challenges presented by IIoT and its companion technologies, underscoring the paramount importance of robust data management strategies. Ultimately, it casts a forward-looking gaze upon the potential of these technologies to reshape industries and revolutionize industrial processes. The objective here is to provide a comprehensive framework illustrating how IIoT, in concert with big data, AR/VR, and blockchain, drives the Industry 4.0 revolution and facilitates the ongoing digital transformation of the industrial landscape.