The objective of the study is to design the fuzzy-based integral sliding mode control, which resolves the stability issues of multi-area interconnected power systems (MAIPS) integrated with wind farm (WF) involving the delays. The contribution can be categorized into two sections. Firstly, the dynamical characteristics of the power system are acquired various factors such as output from the wind generator, the existence of time-delays. The derived model becomes nonlinear due to WF integration and complications occur during the stability analysis. In such a situation, the Takagi–Sugeno (T-S) fuzzy approach is employed to approximate the nonlinear model into linear sub-models. However, the nonlinearities of WF can be linearized at a certain operating point which does not ensure the accuracy of the model. Secondly, to ensure stable performance, the suitable controller scheme becomes necessary and different types of control algorithms are available in the literature for the conventional power system model. This study focuses on designing the controller that copes with the T-S fuzzy model. We design a fuzzy-based integral sliding mode load frequency control (FISMLFC) controller and theoretically validate their performance by utilizing the Lyapunov stability theory and linear matrix inequalities (LMIs). Further, two-area MAIPS is simulated under the experimental values and their results are provided. © 2020 Elsevier Inc.