Organic poultry sector needs high-quality proteins sources to meet specific requirements. The EU’s organic regulation forbids synthetic amino acids; therefore, soybean, with its balanced essential amino acid content, has become the most used protein source, though much of it is imported from non-EU countries, with sustainability and crop competition issues; therefore, it should be substituted with a high-protein-value alternative such as insect meal. In this study, 900 Aviagen Savanna broilers were fed with three different organic diets: soybean only (S100), 50% black soldier fly larvae meal (BSL) and 50% soybean (BSL50), and 100% BSL only (BSL100). Broiler performance, welfare, and fatty acids (FA) were analyzed. BSL50 and BSL100 negatively affected growth, while only BSL100 worsened all of the market-related performances. Meat showed a significant increase in saturated FA (SFA) (p < 0.000) and a corresponding decrease in polyunsaturated FA (PUFA), in BSL50 and BSL100, but α-linolenic acid was not affected by BSL50 treatment (p < 0.000). The SFA increase could represent a negative aspect for human health (e.g., cardiovascular diseases), but, as reported by other authors, medium chain SFA, (i.e., lauric acid), may show beneficial effects as well (i.e., antibacterial, anti-inflammatory and antioxidant properties).