Soil cadmium (Cd) pollution has become a major threat to agricultural production and food security worldwide, especially in industrialized and intensive agricultural regions. Rice (Oryza sativa L.), a staple food crop for more than half of the global population, has a strong tendency to accumulate Cd, which poses significant risks to human health through the food chain. The rhizosphere microbial community, as a vital component of the soil-plant system, plays a crucial role in regulating Cd bioavailability and enhancing plant Cd tolerance, but the adaptive mechanisms of these microbial communities under Cd stress remain unclear. This study investigated the changes in rhizosphere bacterial and fungal communities of rice under three Cd stress levels (no Cd stress, low Cd stress, high Cd stress) using high-throughput sequencing and functional prediction. The results showed that Cd stress significantly altered the rhizosphere microbial community structure, with high Cd stress reducing the microbial Shannon index by 18.7% compared to non-Cd stress conditions. Taxonomically, Cd stress enriched Cd-tolerant taxa such as Pseudomonas, Bacillus (bacteria), and Trichoderma, Mortierella (fungi), while decreasing the relative abundance of Cd-sensitive taxa including Acidobacteriota and Basidiomycota. Functional annotation revealed that pathways related to Cd detoxification (e.g., glutathione metabolism, heavy metal transport proteins), nutrient cycling (e.g., nitrogen fixation, phosphorus solubilization), and plant growth promotion (PGP) were significantly enriched under Cd stress. Redundancy analysis identified soil Cd content, pH, and root exudate components (e.g., organic acids, amino acids) as the key drivers of microbial community shifts. These findings clarify the adaptive strategies of rhizosphere microbial communities to Cd stress and provide a scientific basis for developing microbe-based strategies to remediate Cd-contaminated soils and improve rice Cd tolerance.