Magnesium dilactate is increasingly sought after for its applications in the pharmaceutical, food, and dietary supplement industries due to its essential role in various physiological processes. This study explores a sustainable method for synthesizing magnesium dilactate through lactic acid fermentation using tomato juice, coupling the neutralization of lactic acid with hydrated magnesium carbonate hydroxide. Utilizing the lactic acid bacteria Lactobacillus paracasei and Lactobacillus plantarum, fermentation was optimized in a 50% diluted MRS medium supplemented with glucose and tomato juice supplemented with glucose, yielding a maximum lactate concentration of 107 g/L. Notably, fermentation in diluted media proved more effective than in undiluted tomato juice, highlighting the inhibitory effects of certain organic compounds and the physical nature of the original tomato juice. Post-fermentation, magnesium lactate was crystallized, achieving high recovery rates of up to 95.9%. Characterization of the product through X-ray diffraction and scanning electron microscopy confirmed its crystalline purity. This research underscores the viability of tomato juice as a fermentation substrate, promoting the valorization of agricultural by-products while providing an eco-friendly alternative to traditional chemical synthesis methods for magnesium dilactate production.