Fungal endophytes have been shown to be frequently found within plant tissues and have the ability to promote plant growth. These endophytes interact with their hosts in various ways, from latent pathogenicity to defensive mutualism, from enhancing stress tolerance to promoting plant growth. Within the study, an endophytic fungus from the Citrus limon plant was successfully extracted and evaluated for its plant growth promoting (PGP) traits. The fungal endophyte was specifically identified as Alternaria sp. Apart from showcasing notable enzymatic and antimicrobial properties, the endophyte exhibited diverse abilities in phosphate solubilization, amylase synthesis and cellulose degradation. The endophyte also exhibited varying production levels of indole acetic acid (IAA) and ammonia. The assessment of optimizing the growth of Alternaria sp. through response surface methodology (RSM) involved investigating the effects of pH, incubation temperature and period on its growth kinetics. This study aimed to determine the optimal conditions for promoting the growth of Alternaria sp. by analysing the interaction between these factors. In addition, the potential endophytic isolate was evaluated through a plant bioassay conducted using a soil-pot system. Notably, a notable enhancement was observed in the vegetative growth parameters of both Vigna radiata and Vigna mungo crops when they were inoculated with the isolate.The results indicate that endophytes derived from terrestrial plants play a significant role in enhancing plant growth and can be utilised as inoculants to establish an eco-friendly approach to crop production.