This work presents the economic assessment of an integrated biorefinery process for sequential fermentative production of lactic acid and biogas from food waste. The integrated biorefinery process was compared to single processes for either lactic acid or biogas production. The economic assessment, considering catchment areas from 2000 to 1 million inhabitants, was based on data from real biorefinery plants and carried out using SuperPro Designer ^® 8.0. The consistency of the approach was evaluated through a set of composite indicators. The integrated biorefinery process was investigated for its economic feasibility of producing lactic acid and biogas, the impact of process scale as well as energy use. Outcomes revealed that an integrated biorefinery process contributes more to optimal use of energy and material flows than single processes. Profitability was confirmed for catchment areas larger than 20,000–50,000 inhabitants.