Global environmental issues are becoming increasingly prominent, driving firms and supply chains to adopt green procurement and supply. While green procurement emphasises a firm's procurement function or the selection of environmentally friendly materials and green suppliers, green supply extends outside the firm, emphasising the development and cooperation of green suppliers. Based on a meta-analysis of 25,433 samples from 116 empirical studies across 30 countries, we examine the global implementation of these two green practices and their influence on firm sustainability performance on the basis of four dimensions: financial, environmental, operational, and social. In order to deploy a better knowledge of green practices worldwide, we further investigate the application of two green practices in four distinct contexts: country, industry, firm size, and ISO development. The study results provide insights for firms to develop differentiated implementation strategies for green practices and for governments to formulate differentiated green policies and regulations.