Adenosine recognized for its immunomodulatory, anti-inflammatory, and anti-cancer properties, has limited clinical and commercial applications due to low production levels in Ganoderma lucidum. Enhancing the expression of key biosynthetic genes presents a viable strategy to boost adenosine production through microbial fermentation. This study focused on the cloning, characterization, and overexpression of the key biosynthetic gene 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase ( GlATIC) in G. lucidum. The 1803-bp GlATIC cDNA was inserted into the plasmid pCAMBIA1302 and introduced into G. lucidum protoplasts via PEG-mediated transformation. Protoplasts were prepared using lywallzyme and driselase. Transformants were analyzed for GlATIC expression levels and adenosine content. The transformant OE- GlATIC-14 exhibited a 7.4-fold increase in GlATIC expression compared to the wild-type (WT) strain on the fourth day of culture. Adenosine content in OE- GlATIC-14 increased by 130.6%, reaching 3970.89 µg/g, compared to the WT strain. Additionally, AMP and guanosine levels were elevated in OE- GlATIC-14. The adenosine enhancement rate achieved in this study surpasses that of genetically engineered Bacillus subtilis strains, with the adenosine content being the highest reported among G. lucidum and other fungi. Overexpression of GlATIC in G. lucidum significantly enhances adenosine production and represents a promising strategy for optimizing microbial fermentation of adenosine in G. lucidum.