Life cycle assessment has been used as an analysis tool to help decision-makers plan for mass urbanization and building construction; however, the research to date focuses on either the individual building scale or overall urban scale. Although several methodologies have been applied to both scales, the results have not been reconciled or synchronized. In light of this, this paper first presents a systematic literature review using bibliometric network data to assess state-of-the-art knowledge of the use of LCA at different scales from 1990–2017. Second, the paper identifies the main research foci at the building and urban scales. At the building scale, three research focal points are identified: building materials and products, design solutions, and energy consumption/emissions reduction. At the urban scale, there are three research areas of focus as well: urbanization and infrastructure planning, urban metabolism (water/energy/waste synergy), and complexity of urban issues. Next, the most influential papers and journals are presented. Drawing upon the findings from the literature review, major gaps in current research activities are identified as the building-centric approach, energy performance–centric approach, and lack of consideration for uncertainties. These are critical areas requiring further study and research.