Aims:The application of beneficial microbes is a suitable alternative to synthetic pesticides and fertilizers for agriculture. This study was aimed to evaluate the potential of a selected Trichoderma strain as a biocontrol agent against Rhizoctonia sp. and as a biofertilizer to improve paddy growth. Methodology and results: Four Bipolaris strains were identified via DNA barcoding as the cause of brown spot disease, whereas two Rhizoctonia strains were similarly identified as the cause of sheath blight disease in Brunei Darussalam. Eight Trichoderma strains were initially screened using confrontation assay and were found to substantially inhibit the growth of Rhizoctonia sp. Hybrid rice named BDR5 was treated with Trichoderma sp. UBDFM01 and/or Rhizoctonia sp. It was found that the selected strain showed the potential as a biofertilizer by significantly increasing the vigour index I, chlorophyll a, chlorophyll b, total chlorophyll and dry shoot weight of the rice plants. The pathogen negatively affected the plants by significantly reducing the vigour index II, chlorophyll a, chlorophyll a/b ratio, total chlorophyll, and total weight of grains. Trichoderma strain showed the potential as a biocontrol agent by significantly diminishing the negative effects of the pathogen on the chlorophyll a, chlorophyll a/b ratio and total chlorophyll. Conclusion, significance and impact of study:This study highlights the potential of Trichoderma sp. UBDFM01 as a biocontrol agent against Rhizoctonia sp. and also as a biofertilizer for rice plants. In addition, this study is the first to provide DNA-based evidence of Bipolaris sp. and Rhizoctonia sp. as the fungi that caused rice diseases in Brunei Darussalam.