The pursuit of alternative ingredients with improved environmental sustainability, nutritive value, and cost efficiency is crucial for modern pork production systems. Replacing soybean meals has the potential to reduce environmental impacts. This study proposes a substitution framework in which alternative ingredients are introduced to replace a growing proportion of soybean meals based on net energy equivalence. Additionally, an optimisation framework has been proposed that simultaneously addresses multiple objectives, including cost, feed weight, environmental impacts, and essential nutritional requirements. Eighteen feed mixes were obtained by introducing alternative ingredients selected from an extensive, if not systematic, literature review. Therefore, black soldier fly meal (BSF), bakery by-product (BP), and pea (P) have been introduced in feed mixes, and feed mixes were evaluated across ten environmental impact categories via a life cycle assessment (LCA) approach (ISO 14040-44), with two different functional units: 1 kg of feed mix and 1 kg of pig meat at the slaughterhouse. To assess the robustness of the optimised feed mixes under uncertainty, a cost and climate change sensitivity analysis was conducted. The results demonstrated that the introduction of BSF increased costs and environmental impacts at the single-score level (by 280% and 118%, respectively), with differences at the single-impact category level. In contrast, BP and P emerged as the most effective solutions in the substitution and optimisation approaches, respectively. BP contributed to a reduction in environmental impacts of up to 9% in optimised diets, while P achieved economic cost savings of up to 28% compared to the original diet. These findings highlighted the need to strike a balance between environmental benefits and financial viability, underscoring the importance of policy support and market incentives to make sustainable practices more accessible.