Evaluation of the prebiotic properties of rice samples and the commercial standards (inulin and β-glucan) showed that these were enhanced on the germinated Riceberry rice (GR), and germinated Riceberry rice with mycelium (GRM) treatments. Results also showed the improvement of prebiotic properties on GR as the R sample did not show any prebiotic properties in all probiotic bacteria, whereas the GR sample showed moderate prebiotic activity scores of 0.40, 0.88, and 0.56 on Pediococcus sp., L. acidophilus, and S. lactis, respectively. Furthermore, the prebiotic activity of GR was improved when fermented with Pleurotus ostreatus mycelium. For further applications, the GRM could be used on rice-based products, such as rice flour, rice crackers, or other rice products to enhance nutritional value and improve digestive system health, especially in the elderly.