The revolution brought about by intelligent Internet of Things (IoT) systems has impacted every sphere of life, including but not limited to smart healthcare, grid, home, industry, logistics, and environmental monitoring. IoT systems traditionally are plagued with security vulnerabilities and scalability issues. In recent years, blockchain technology has widely emerged as a potential solution for secure, trusted, and efficient storing, processing, and data sharing. This article aims to incorporate IoT in conjunction with blockchain by introducing an intermediary layer in the IoT ecosystem. Thus, an intelligent blockchain-enabled IoT (BIoT) framework is proposed for smart applications to provide data reliability, privacy, and scalability in IoT ecosystems. Moreover, several real-life BIoT case studies are highlighted and comparatively analyzed to discuss the contribution of our proposed layer vis-á-vis conventional blockchain-IoT ecosystems. Finally, based on the analysis, we outline some futuristic directions and open challenges for the BIoT.