Endophytic fungi have been considered as strong plant growth promoters due to phytohormones production. The current study reports the isolation of endophytic fungi from bio-prospective medicinal plant cannabis sativa. Endophytic fungus Bipolaris sp. CSL-1 from the leaves of C. sativa was isolated. Culture filtrate (CF) was primarily investigated for indole-3-acetic acid (IAA) and gibberellins (GAs) and was further evaluated for its capability to enhance mutant Waito-C rice growth attributes. A variety of plant growth characteristics, including seedling length, seedling biomass, and chlorophyll content, were significantly promoted by the CF, and the growth-promoting effect was due to IAA and various GAs in the CF. Gas chromatography/mass spectrometry analysis revealed the quantities (ng/mL) of various GAs, including GA₁ (0.758 ± 0.005), GA₃ (0.00015 ± 0.005), GA₄ (0.945 ± 0.081), GA₇(0.6382 ± 0.012), GA₉ (0.0125 ± 0.0002), and GA₂₄ (0.0139 ± 0.0013). Similarly, endogenous GA₄ (33.243 ± 4.36), GA₂₄ (29.64 ± 2.68), GA₇(22.5 ± 1.3), and GA₁₂ (25.21 ± 2.8) were significantly upregulated in rice mutant after CF application. Furthermore, RT-PCR indicated that IAA and GA pathway genes (des, ggs2, P50-1, P450-4, and iaaH) were expressed in CSL-1 and the combined application of CSL-1 spore suspension with yucasin and uniconazole to maize seedlings revealed that CSL-1 such as exogenous GA₃ and IAA alleviated the negative effect of uniconazole and yucasin and promoted maize-seedling growth. These findings suggest that the endophytic fungus CSL-1, which produces IAA and GAs, can play a vital role in promoting plant growth and that CSL-1 could be used to enhance crop growth and mitigate plant stress under a variety of environmental conditions.