Acid mine drainage (AMD) is a highly acidic solution containing several toxic HMs resulting from the oxidation of sulphide minerals exposed during mining. AMD is of particular environmental concern due to its extremely low pH (typically <3) and high heavy metals concentration (reaching several hundred ppm) posing risks to water sources, and its remediation has prohibitive costs. Chemical neutralisation is the most common remediation strategy. Nonetheless, this route generates a huge amount of sludge, and does not address the heavy metals challenge. Inorganic polymers might be a sustainable and low-cost alternative to control AMD pH, while simultaneously immobilising the heavy metals in their structure. In the present work, red mud-containing inorganic polymers were used for the first time to treat ADM from a Portuguese mine. Results show that this innovative approach, involving a toxic waste to produce samples able to treat AMD wastewaters, is not only feasible, but highly effective.