The increasing demand for sustainable protein resources in aquaculture has prompted the exploration of alternative feed ingredients, such as mealworm (MW; Tenebrio molitor). This study evaluates the effects of MW inclusion on the fatty acid composition and proximate analysis of Pacific white shrimp (Litopenaeus vannamei) during a 60-day feeding trial involving juvenile shrimp, which were assigned to five experimental diets with varying MW inclusion levels: T₀ (0% MW), T₁₅ (15% MW), T₃₀ (30% MW), T₆₀ (60% MW), and T₁₀₀ (100% MW), all formulated to maintain a protein content of approximately 37%. Proximate analysis indicated that fishmeal (FM) contained a crude protein level of 56.31%, while MW had a comparable content of 53.10% (p>0.05). However, FM demonstrated significantly higher levels of digestible protein, ash, and nitrogen-free extract (NFE) compared to MW, which was characterized by higher lipid and fiber contents. The analysis of shrimp muscle composition revealed that increased MW inclusion (T₃₀-T₁₀₀) significantly enhanced crude protein levels (p<0.05), while T₀ showed the highest crude lipid content (p<0.05). FA profiling indicated that FM was abundant in essential long-chain polyunsaturated fatty acids (PUFAs), including eicosapentaenoic acid (EPA; 8.54%) and docosahexaenoic acid (DHA; 13.57%). Conversely, MW lacked these essential FAs, leading to a decrease in EPA and DHA levels in shrimp muscle as MW inclusion increased. The predominant FAs in shrimp muscle shifted towards oleic acid (C18:1c), particularly in the T₁₀₀ treatment. The findings of this study indicate that increased inclusion of MW significantly enhances the crude protein levels in Pacific white shrimp while concurrently leading to a decrease in essential fatty acids such as EPA and DHA. This highlights the necessity for dietary supplementation with alternative lipid sources to meet the essential fatty acid requirements of L. vannamei.