Having a consensus for decision making in swarm UAVs in critical systems has been a significant challenge. In this research, we propose a blockchain-based consensus mechanism for autonomous target selection in military drone swarms. The system integrates reputation-weighted voting, cross-sensor validation, and Byzantine fault tolerance to enable decentralized decision-making. Adjustable thresholds, which as 60% for normal missions, 70% for critical missions, and dynamic reputations ensure robustness. This work bridges the gap between decentralized trust and real-time operational efficiency in autonomous swarm UAV systems.