Integrated biorefinery is a process facility that converts biomass into value added products with maximum energy and material recovery. It has the ability to provide strong, self-dependent, sustainable and environmentally benign alternatives for the production of bulk and fine chemicals. However, there is a need for a methodology capable of evaluating the integrated processes in order to identify the optimal products possible to be obtained from biomass and the best synthesis routes for producing them. To address this issue, a systematic methodology for optimal product design in an integrated biorefinery is presented in this work. To illustrate the proposed approach, a proof of concept example is presented.