This paper is concerned with the problem of stability of two‐dimensional (2‐D) switched Takagi‐Sugeno (T‐S) fuzzy systems with stable and unstable subsystems described by the Roesser model with constant delays. The T‐S fuzzy model is applied to close the discrete‐time nonlinear subsystems. By utilizing the definitions of mode‐dependent average dwell time (MDADT) method and a quasi‐alternative switching signal, the stability condition for 2‐D discrete‐time switched systems composed of stable and unstable subsystems is derived, and a study on one‐dimentional (1‐D) system can be seen as a special case. Finally, the effectiveness and advantage of the obtained results are illustrated through practical example by LMI toolbox.