Various eco-friendly materials are used in the construction industry. South Korea employs the Green Standard for Energy and Environmental Design (G-SEED), a green building certification system, in which materials account for 11% of the evaluation criteria. However, data for each eco-friendly material are managed individually by different institutions, causing inefficiency, increased costs, and potentially greater environmental impacts associated with material and resource selection. Hence, this study develops a green building materials integrated platform (GIP) that collates information on eco-friendly materials across different industries in South Korea, to support the G-SEED evaluations. Guidelines and standards related to each evaluation item were analyzed and used to compile a green building materials database. The database includes 12,636 data points representing product prices and environmental impact data. This database was used to develop the four-level Excel-based GIP. Case studies were conducted on actual G-SEED buildings to analyze the economic efficiency and environmental performance achieved by using alternative materials to those recommended by the GIP. Case 1 exhibits improvements in economic efficiency and environmental performance of 17% and 10%, respectively, whereas Case 2 exhibits improvements of 8% and 21%, respectively. Thus, both case studies boast superior combinations of green building materials compared to existing alternatives.