Nickel contamination in textile wastewater poses a significant environmental threat because to its toxicity, persistence, and capacity to bioaccumulate in aquatic habitats. The textile industry emits significant quantities of heavy metals during dyeing and finishing procedures, with nickel identified as one of the most perilous contaminants. Exposure to nickel-contaminated water can lead to severe health issues, including organ damage and other chronic impacts, as well as disrupting aquatic ecosystems. Traditional treatment procedures, including chemical precipitation, ion exchange, and membrane filtration, are effective but frequently costly and may produce secondary waste. Consequently, there is an increasing demand for sustainable and eco-friendly solutions. This study examines the application of pomegranate peel, a by-product of juice and food processing industries, as an environmentally sustainable adsorbent for the extraction of nickel from textile effluent. The peel was harvested, desiccated, pulverized, and treated before to its application in batch adsorption studies. The influences of pH, contact duration, adsorbent quantity, and starting nickel concentration were analyzed. The findings demonstrated a notable drop in biochemical oxygen demand (BOD) of 68–75%, signifying a considerable decrease in biodegradable organic matter. The chemical oxygen demand (COD) decreased by 72–80%, indicating the elimination of oxidizable contaminants. Total dissolved solids (TDS) diminished by 55–63%, illustrating the adsorbent's efficacy in mitigating dissolved pollutants. The pH of the wastewater was modified from an initial alkaline range of 8.5–9.0 to a near-neutral range of 6.8–7.2 post-treatment. Moreover, dissolved oxygen (DO) levels increased by 40–48%, signifying improved water quality following adsorption. The results validate that the pomegranate peel-derived adsorbent successfully eliminates nickel (up to 95%) and improves the overall quality of the treated wastewater.