This paper proposes an optimal tuning of Proportional Integral Derivative (PID) controller using Bacterial Foraging Optimization Algorithm (BFOA), to enhance the control performances and stability of Automatic Voltage Regulator (AVR) system. A new objective function designed with necessary time domain specifications is considered in this research work for tuning the gain parameters of PID controller. The effectiveness of the proposed BFOA tuned PID controller is extensively absorbed by analyzing the output performance, stability and robustness of the system. The superiority of the proposed approach is distinctly demonstrated by comparing their results with recently documented results of Swarm Intelligence (SI) techniques such as Differential Evolution (DE), Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC) algorithms and Many Optimizing Liaisons (MOL) algorithm.