In accordance with the Sustainable Development Goals of the United Nations, the Environmental Impact Assessment (EIA) is the main management tool used to identify and prevent the impact of productive activities on the environment and human health and promote compensation measures. Metallic mining is the main productive sector in Chile. In 2021, Chile was the highest global producer of copper, the second-highest producer of molybdenum, and the third-highest producer of silver. Other types of non-metallic mining, such as siliceous aggregates, iodine, and hydrocarbons, are also notable. Mining activity requires robust and flexible environmental legislation. This paper analyzes the performance of the Chilean EIA system regarding mining projects entered into the system as Environmental Impact Declarations (EIDs) for low-incident projects and Environmental Impact Studies (EISs) for high-incident projects. The 2867 mining projects submitted to the Chilean EIA system as EIDs (91.8%) and EISs (8.2%) between 1994 and 2019 were compiled. For a proper performance evaluation, a representative sample of 68 projects (61 EID and 7 EIS) was studied through a principal coordinate analysis using eleven indicators widely used in the EIA scientific literature. The results do not show significant differences between the EID and EIS projects or remarkable differences regarding the increasing restrictions introduced by the successive regulatory periods SD30, SD95, and SD40. Based on the observed weaknesses, four opportunities for improvement are proposed focused on creating a simplified sanctioning procedure, upgrading the form of delivery of the project monitoring information, early citizen participation, and incorporating the climate change variable into the projects. This paper extends the methodology introduced in previous papers to evaluate the performance of the Chilean EIA system in mining projects, seeking also to offer a feasible methodology to other countries with a similar socio-economic context or other productive sectors potentially impacted by the degradation of land and renewable natural resources.