<p>The fish processing industry frequently disposes of byproducts such as skin, scales, and bones, viewing them as waste. However, these byproducts are rich in protein, particularly collagen, which can be transformed into gelatin. This study seeks to determine the optimal conditions for extracting gelatin from the discarded skin of longtail butterfly rays (<i>Gymnura poecilura</i>). To achieve this, a central composite design featuring four factors and five levels was used to analyze the influence of pretreatment time in acid and alkali solution (<i>A</i>), skin-to-water ratio (<i>B</i>), extraction temperature (<i>C</i>), and extraction time (<i>D</i>) on yield (<i>Y</i>). The most critical factors impacting the yield were identified as pretreatment time, extraction temperature, and extraction time. The optimized conditions for the maximum gelatin yield (22.7%) were 30&#xa0;min of pretreatment time followed by 5&#xa0;h of extraction time at 60&#xa0;°C extraction temperature. The optimized gelatin exhibited a protein content of 90.25%, along with 6.30% moisture and 0.23% ash content. Fat was not detected in ray gelatin. Analysis of the ray gelatin indicates that its proximate composition meets acceptable standards in relation to commercial porcine gelatin. The ray gelatin manifested a higher gel strength (288&#xa0;g) and viscosity, 7 cP, than commercial porcine gelatin (<i>p</i> &lt; 0.05). The FTIR spectra of ray gelatin reveal absorption bands predominantly located in the amide band region, specifically amide A, amide B, amide I, amide II, and amide III, which are comparable to those found in commercial gelatin. This investigation successfully refined the gelatin extraction process by pinpointing the best conditions for maximizing the yield. The results demonstrate that ray fish skin can be an excellent alternative source for gelatin production, contributing to a sustainable and beneficial application for marine byproducts.</p>