This paper deals with an $H_{infty}$ output feedback controller design for uncertain singularly perturbed T-S fuzzy systems. Integral quadratic constraints are used to describe various kinds of uncertainties of the plant. It is shown that the $H_{infty}$ norm of the uncertain singularly perturbed fuzzy system is less than $gamma$ for a sufficiently small $varepsilon$ > 0 if the $H_{infty}$ norms of both the slow and fast subsystem are less than $gamma$. Using this fact, we develop a linear matrix inequality based design method which is independent of the singular perturbation parameter $varepsilon$. A numerical example is provided to demonstrate the efficacy of the proposed design method.