This paper discusses the problem of semi-global decentralised output feedback control for a class of uncertain nonlinear systems. Based on the ideas of the homogeneous systems theory and the adding a power integrator technique, we first design a homogeneous observer and an output feedback control law for each nominal subsystem without the nonlinearities. Then, using the homogeneous domination approach, we relax the linear growth condition to a polynomial one and construct decentralised stabilisers to render the nonlinear system semi-globally asymptotically stable. Two simulation examples are provided to show the effectiveness of the control scheme.