Cooperative output regulation is a general framework, which considers output synchronisation, homogenisation and disturbance rejection simultaneously. To be an extension, this study divides the lumped disturbance into two parts, namely, local disturbance which is slow-varying, mismatched and non-linear, and global disturbance generated by an autonomous linear system. Generalised extended state observers (GESOs) are constructed to estimate the local states, the local disturbances and the global disturbance simultaneously. Observer-based controllers are designed to realise cooperative output regulation in the presence of mismatched uncertainties. In control design, a linear matrix inequality-based design methodology is proposed to get the exponentially convergent GESO with guaranteed decay rate. A simulation example is then shown to validate the theoretical results.