The textile industry produces liquid waste containing synthetic dyes, such as Remazol Yellow FG, which are difficult to decompose naturally and negatively impact the environment. This study aims to evaluate the effectiveness of biochar derived from coffee fruit shell waste as an adsorbent for removing Remazol yellow FG dye from aqueous solutions. The method used includes pyrolyzing coffee fruit shell at 300°C for 120 minutes to produce biochar, which is then tested for its dye adsorption capacity through batch experiments with varying dye concentration, pH levels, and contact time. The results showed that coffee fruit shell biochar had a high adsorption capacity at pH 4 and a contact time of 80 minutes. The process of adsorption followed the Langmuir isotherm model with a value (r2) of 0.91507 for non-active biochar adsorbent and 0.92372 for biochar that had been activated with NaOH. Adsorption kinetics followed second-order kinetics with r2 reaching 0.96189 for non-active biochar and 0.96697 for biochar activated with NaOH. The effectiveness of biochar under laboratory conditions highlights its potential as a more economical and environmentally friendly adsorbent compared to commercial activated carbon. This research contributes to the development of liquid waste treatment technologies based on renewable materials, supporting the circular economy in the textile industry.