Plant-based foods are essential to the human diet and offer solutions to health, environmental, and economic challenges. Plant proteins, especially when fermented, become more nutritionally complete. Controlled microbial fermentation enhances food quality and safety, suppresses anti-nutritional factors like phytic acid, and enables the development of innovative, functional food products. The objective of this study was to investigate the microbial fermentation of carob seeds (Ceratonia siliqua L.), a xyrophytic plant widely distributed across Mediterranean countries, and their potential applications in the food industry. These seeds were primarily selected and dried and then fermented in lab-scale solid-state type fermentation by lactic acid bacteria, Saccharomyces cerevisiae (yeast) and Aspergillus oryzae (fungus) for four days. The fermented carob seeds were then analyzed for the following: a) in-vitro digestibility was tested by applying appropriate proteolytic enzymes and measuring pH decrease, b) concentration of phytic acid was calculated through a biochemical assay that included measurements of free and total phosphorus and c) protein electrophoresis was applied to analyze the degree of fragmentation of the fermented proteins from carob seeds. The results have shown a mild proteolytic activity exerted by the microbial fermentation of the carob seeds which was evident in the in-vitro digestibility study and the decrease of the concentration of phytic assay. However, protein electrophoretic patterns have not revealed new protein zones as evidence of protein hydrolysis due to seed fermentation. Further research is needed to establish the optimum conditions for solid-state microbial fermentations of carob seeds to obtain a more digestible source of protein.