Smooth output feedback stabilization problem for a family of planar switched nonlinear systems is addressed. First, based on the adding a power integrator technique, the tasks of finding a common Lyapunov function and designing state feedback stabilizing control laws are accomplished simultaneously. Then, combining the state feedback control laws and the reduced-order nonlinear observers, output feedback control laws are designed to globally stabilize the switched nonlinear system under arbitrary switchings, whose subsystems may have uncontrollable/unobservable Jacobian linearizations. (C) 2017 Elsevier Ltd. All rights reserved.