This article deals with the codesign of an output-dependent switching function and a full-order affine filter for discrete-time switched affine systems. More specifically, from the measured output, the switched filter has the role of providing essential information for the switching function, which must assure global practical stability of a desired equilibrium point. The design conditions are based on a general quadratic Lyapunov function and are expressed in terms of linear matrix inequalities. Moreover, whenever the system is quadratically detectable, the solution to the output feedback problem coincides with the one for the state feedback case and the associated filter admits the observer form. To the best of the authors knowledge, this is the first time that the dynamic output feedback control problem is treated in the context of discrete-time switched affine systems. The results can be used to cope with sampled-data control and have the property of assuring global asymptotic stability when the sampling period tends to zero. A practical application concerning the velocity control of a dc motor driven by a buck-boost converter illustrates the theoretical results.