The adoption of blockchain technology across financial, industrial, and IoT ecosystems has increased the demand for reliable and scalable consensus mechanisms. Traditional Practical Byzantine Fault Tolerance (PBFT) offers strong consistency and finality but scales poorly due to high message complexity and communication overhead. To address this, we propose Reliable Practical Byzantine Fault Tolerance (rPBFT), a consensus mechanism that improves performance and fault tolerance in large-scale distributed systems. rPBFT evaluates node reliability through message exchanges during consensus and dynamically forms a committee based on reliability scores. This reduces communication load, improves scalability, and prevents performance degradation caused by faulty nodes while maintaining decentralization without representative election. Experiments evaluated rPBFT against PBFT and HotStuff. In fault-free environments, PBFT achieved better performance due to the absence of reliability computation overhead. Under faulty conditions, rPBFT outperformed PBFT and HotStuff, achieving 30%–40% lower latency, 50%–80% higher throughput, and a 33% improvement in consensus success rate. In fault-tolerance tests, rPBFT maintained stable throughput as the Byzantine ratio and network fault ratio increased, demonstrating resilience via a reliability-based recovery model. These results confirm that rPBFT enhances scalability and robustness while preserving the core properties of Byzantine fault-tolerant consensus, making it well-suited for large-scale blockchain and IoT environments.