In this study, a novel and cost-effective adsorbent, sulfonated modified rice straw (SRS), was developed for the selective adsorption and extraction of gold ions from acidic solutions. The SRS was synthesized through a simple and environmentally friendly sulfonation crosslinking modification process, leveraging the abundant and low-cost agricultural waste, rice straw. The surface of SRS was functionalized with sulfonic acid groups, which, under acidic conditions, exhibited positive charges that facilitated the electrostatic adsorption of negatively charged AuCl4- ions. Concurrently, the hydroxyl groups within the adsorbent structure donated electrons, reducing the adsorbed AuCl4- ions to metallic gold. SRS showed excellent adsorption selectivity and high adsorption efficiency for gold under different experimental conditions. The adsorption kinetics and isotherms of SRS for gold were well-described by pseudo-second-order and Langmuir models, respectively, indicating a chemisorption process predominantly governed by the electronic interactions and active sites on the SRS surface. The maximum adsorption capacity of SRS for gold was determined to be 88.81 mg/g in a 1 M HCl medium, showing its superior performance compared to other reported adsorbents under similar acidic conditions. An economic evaluation revealed that the SRS-based gold recovery process is financially viable, with a potential net profit of $71 per cubic meter of degoldized solution processed. Sulfonated modified rice straw adsorbent presents a promising and sustainable approach for the selective recovery of gold ions from complex acidic solutions, offering significant potential for application in the gold extraction industry.