In the light of microalgae rich in proteins, carbohydrates, and lipids, development of multi-product biorefinery from microalgae has become a promising approach towards commercialization of microalgae-based products. This review discusses an integrated algal biorefinery (IABR) based on a combination of four microalgae-to-products chains for the production of biofuels, biopower, and byproducts. Two systematic analytical approaches by life cycle assessment (LCA) and techno-economic assessment (TEA) are used to quantify the economic and environmental benefits. From process systems engineering (PSE) aspects, the approach procedures include that (i) the engineering process model serves as the foundation for assessment, (ii) an IABR is generated via process design, simulation, and integration, and (iii) the multi-objective optimization of an IABR with respect to economic and environmental issues is addressed.