Glioblastoma multiforme (GBM) remains one of the most aggressive and treatment-resistant brain tumors, characterized by a hostile microenvironment and poor prognosis. Recent advances in synthetic biology have led to the engineering of Escherichia coli (E. coli) strains as living therapeutics capable of targeting GBM via reactive oxygen species (ROS)-mediated mechanisms. This systematic review evaluates the mechanisms by which engineered E. coli modulate ROS, their therapeutic efficacy in preclinical models, and challenges in delivery, safety, and regulation. Engineered strains show promise through prodrug conversion, direct ROS production, and immune activation, especially when combined with nanocarriers and immune checkpoint inhibitors. However, tumor heterogeneity, biosafety concerns, and regulatory complexities remain significant hurdles. Advancing toward clinical translation will require robust biocontainment systems, adaptable genetic circuits, and validation in humanized preclinical models.