© 2017 The Authors There has been an increasing interest in corporate sustainability (CS) and how companies should strive for it in order to satisfy stakeholders’ demands concerning social, economic, and environmental impacts. The purpose of this paper was to identify the best sustainability practices and the sustainability maturity levels that allow manufacturing and service companies to contribute to sustainable development in the long run. Based on a qualitative approach, a comparative study of five large companies was deployed in order to determine their sustainability maturity levels and best practices. The research method consisted of a critical review of the literature and category analysis concerning corporate sustainability trends and some of the best well-known performance frameworks such as the Global Reporting Initiative (GRI), business excellence models (BEMs), and international standards. The main findings reveal that companies’ sustainability maturity levels range from satisfactory to sophisticated in several sustainability aspects. Best sustainability practices found in this sample include the use of certifications such as ISO 9000, ISO 14001, GRI, and CSR, among others, combined with the systematic use of BEMs over many years. Finally, several key processes such as self-assessment, benchmarking, corporate reporting, strategic planning, and systematic training were found to be significant in helping manufacturing and service organisations achieve their business sustainability objectives.