Background: Development of objective, quantitative sustainability reporting scores for international companies has to be based on legal, regulatory, and public policy standards as well as focused exclusively on environmental, social, and governance (ESG) issues. The key performance indicators (KPIs) developed here differ from traditional agencies’ rating schemes in that they are equally applicable across industrial sectors. They measure performance in terms of several environmental Global Reporting Initiative (GRI) indicators. The KPIs quantify performance by systematically linking corporate revenues with sustainability metrics, thereby yielding readily comparable, numerical scores. Methods: This report illustrates their utility with data on carbon dioxide (CO2) emissions from leading companies within the S&P Global ESG ranking for 2023. Results: The findings reveal significant gaps in managing Scope 3 emissions, which dominate the value chain and present the greatest challenge for corporate sustainability. These disparities highlight the need for improved data transparency and harmonized reporting standards to ensure consistent and actionable sustainability assessments. Conclusions: By bridging these gaps, the KPIs enable more equitable comparisons across industries and encourage better alignment of corporate strategies with global climate objectives. The additional transparency and insights in turn afford investors, managers, policy makers, and other stakeholders’ better information for their decision making.