The present work primarily addresses a maiden application of fractional order calculus‐based cascade tilt‐integral–tilt‐integral‐derivative (CC‐TI‐TID) controller in load frequency control of deregulated power systems. Simultaneously, an efficiency test of a recently introduced water cycle algorithm (WCA) in obtaining optimal setting of CC‐TI‐TID controller is also investigated. In the proposed controller, TID controller acts as a slave controller, while TI controller played a role of master controller. Performance test of the proposed controller in stabilizing system frequency of a deregulated four‐area power system is carried out. In view of the above, firstly, superiority of WCA over other studied algorithms such as genetic algorithm, differential evolution, and teaching‐learning–based optimization techniques is established considering the proposed CC‐TI‐TID controller‐assisted four‐area power system. Secondly, comparative performance among WCA tuned proposed CC‐TI‐TID, CC‐PI‐TD, and PID controllers are explored in terms of chosen objective function, performance indices, settling time, and peak deviations. The comparative results obtained reveal that WCA tuned CC‐TI‐TID controller outperforms the others. Further, to check the robustness of the CC‐TI‐TID controller, sensitivity analysis is performed by varying Disco participation matrix.