In resource-constrained Internet of Things (IoT) environments like Low-power and Lossy Networks (LLNs), efficient communication protocols are essential. In this context, IP multicast protocols play a crucial role, facilitating the transmission of data packets from a single source to multiple recipients, thereby conserving bandwidth, power, and time for numerous LLN applications, such as over-the-air programming, information dissemination, and device configuration. Despite their usefulness, existing multicast solutions face several challenges, including scalability, energy efficiency, and reliability. To tackle such issues, this paper introduces Protocol Independent Multicast for LLNs (PIM-LLN). PIM-LLN employs a multicast distribution tree anchored at the border router, a multi-path data dissemination mechanism, and an efficient retransmission technique to route streams exclusively to regions with group members reducing energy consumption and bandwidth usage while improving response times and reliability. Through comprehensive simulations and public testbed experiments, we meticulously assess PIM-LLN’s performance, benchmarking it against state-of-the-art solutions under different scenarios. Our findings underscore the scalability, reliability, reduced latency, and efficient resource utilization of PIM-LLN in terms of memory, bandwidth, and energy. Notably, PIM-LLN, as compared to state-of-the-art solutions, achieves a similar level of reliability while reducing overhead by up to 50%.