Energy constrained feature of sensor nodes, hostile environment over which it is deployed for monitoring and the necessity to make reactive decisions introduce crucial challenges in Wireless Sensor Networks (WSNs). They demand energy utilization to be optimized for extending network lifetime. Unequal cluster-based routing is identified to be the most significant methodology, which when adopted in WSNs helps in reducing the degree of energy utilization without impacting the longevity of the network. In this paper, an Unequal Cluster-based Routing Mechanism using Lyrebird Optimization Algorithm (UCRMLOA) is proposed for improving energy efficiency which helps in preventing the formation of energy holes and improving network longevity. This UCRMLOA approach is proposed by mimicking the natural behaviour of Lyrebird in the event of danger which is analogical to the process of exploration and exploitation introduced during clustering and Cluster Head (CH) selection. It specifically uses Lyrebird Optimization Algorithm (LOA) for forming clusters that effectively balances energy in the network. It uses a fitness function that uses parameters such as number of sensor nodes selected as relay, distance between the selected CHs and the sink, Residual Energy (RE) for CH selection and subsequent optimal route determination. It is also proposed as a potential approach that balances the network traffic load efficiently such that formation of energy holes is completely prevented for maximizing network lifetime. The results of UCRMLOA for varying number of sensor nodes confirm 22.1% better sustenance of alive nodes, 24.76% minimized energy consumption and 20.42% reduced packet delay in contrast to baseline approaches considered for evaluation.