Hitherto, the evolution of mobile networks have fulfilled the increasing demands for enhanced performance, availability, portability, elasticity, and energy efficiency posed by the ever growing network services. In line with the progression, 5G depicts the next generation of mobile networks that further promises remarkable performance improvements as well as creation of new value chain. In parallel to 5G, the Internet of Things (IoT) has emerged as another new paradigm for interconnection of massive communication-capable heterogeneous smart objects. 5G is envisaged to broaden IoT's scope and fields of applicability. However, since current mobile networks and also more general IoT systems are based on centralized models thus it is anticipated that they will face tremendous challenges to meet-up the requirements of future 5G-enabled-IoT use cases. To solve these inevitable issues Blockchain stands out as promising technology. Some of the offerings of Blockchain technology are immutability, non-repudiation, proof of provenance, integrity, privacy, etc. Blockchain's combination with 5G and IoT still requires essential insights with respect to concrete application domains, scalability, privacy issues, performance, and potential financial benefits. The paper aims to elaborate and emphasize the key aspects of the use of Blockchain for 5G and IoT.