This paper employs the direct method to design sampled-data state/output feedback controller for a class of uncertain nonlinear systems under a general linear growth condition. Both state feedback controller and observer are constructed directly in the discrete-time domain for the difference-integral systems equivalent to the continuous-time systems. To dominate the influence of the uncertain nonlinearities, a co-design process is used to determine the sampling period and scaling gain together. Compared to the emulation method, the direct co-design method can handle a broader class of nonlinear systems and has more flexibility in choosing the sampling period that is less restrictive for digital implementation.