The tumor microenvironment comprises a multifaceted ecosystem encompassing a dynamic interplay between malignant cells, non-neoplastic counterparts, extracellular matrix constituents, and intricate microbial communities. In particular, microorganisms have established a pervasive presence within tumor masses, exhibiting a marked predilection for distinct spatial niches. The intricate amalgamation of their composition and multifaceted functional profiles assumes a commanding role in orchestrating the intricate ballet of tumor genesis and advancement. In this comprehensive review, we endeavor to illuminate the intricacies of intratumoral microbiota, unraveling the intricate molecular mechanisms that underpin its profound influence on the initiation and relentless progression of neoplastic growth. By doing so, we unveil a panorama of novel perspectives that hold promise in revolutionizing both diagnostic paradigms and therapeutic modalities for tumors.