<p>Copper slag is a critical secondary resource with a global annual production of approximately 40 million tons. It contains significant concentrations of Fe (35–45 wt.%) and Cu (0.50–2 wt.%), with grades substantially exceeding those of certain low-grade ores, alongside valuable companion metals such as Zn, Co, and Ni. However, the current industrial utilization rates for Cu and Fe from this slag remain remarkably low, at less than 12% and 1%, respectively. This paper provides a systematic review of the research progress and technical bottlenecks in the metallurgical recovery and comprehensive utilization of copper slag. Analysis reveals that while mineral processing can achieve Cu recovery rates exceeding 94%, it is severely hindered by the extreme abrasiveness and high Bond work index of the slag, leading to prohibitive grinding energy consumption and equipment depreciation costs. Hydrometallurgical leaching allows for Cu and Zn extraction rates above 90%, yet it faces bottlenecks such as silica gel formation impeding filtration and excessive acid consumption caused by the massive dissolution of fayalite. Although pyrometallurgical roasting-magnetic separation can yield high-grade Fe concentrates with recovery rates over 90%, the requirement for high-temperature operations (1000–1400 ℃) results in immense energy consumption, significant carbon emissions, and high capital investment. Furthermore, the application of copper slag in construction materials, such as cement and glass–ceramics, is constrained by concerns over long-term durability, heavy metal leaching risks, and high-sulfur impurities that compromise thermal stability, thereby limiting market acceptance. Improved processes characterized by high recovery efficiency, low energy consumption, and minimal secondary pollution remain the primary focus of research and development. Scalable, ecofriendly, and high-efficiency utilization technologies are currently limited and warrant further investigation.</p> Graphical Abstract <p></p>