High-performance biological sensing and modulation are essential for uncovering fundamental biological processes and enabling a range of downstream biomedical applications. Miniaturized electronics enabled by nanomaterials, which offer advanced stability, resolution, and spatiotemporal specificity, have emerged as promising tools to achieve these goals. However, the complexity of biological systems, with their intricate and multi-scale interactions with nanomaterials, poses significant challenges for nanoelectronics in delivering biologically significant performance and functionality to meet diverse needs. Building on recent progress in nanoscience and bioelectronics, my PhD work has focused on understanding electrical transduction properties at nano-bio interfaces and applying this knowledge to develop graphene-enabled, high-performance bioelectronics to address these challenges across various biological systems, including micro-biofluids, biomolecules, and cells. For micro-biofluids, I will show that graphene single microelectrodes, which harvest charge from continuous aqueous flow, provide an effective biofluid flow sensing strategy. In particular, over six-months stability and sub-micrometer/second resolution in real-time quantification of whole-blood flows with multiscale amplitude-temporal characteristics are obtained in a graphene microfluidic chip. For biomolecules, I will demonstrate that oscillational DNA strands tethered to a graphene transistor, driven by an alternating electric field, induce transistor-current spectral characteristics that resist interference interactions. These spectral characteristics enable DNA sensing with ultrahigh specificity and a detection limit improvement of two orders of magnitude compared to typical methods. Besides, I will discuss a model suggesting that the high specificity and sensitivity of our approach are due to the inherent difference in pliability between unpaired and paired DNA strands. At the cellular scale, I will present a microdevice that integrates microelectrolytic pH modulation with graphene-nanoelectronic pH sensing functions, enabling real-time regulation of cell-microenvironmental pH with high spatial specificity and pH precision. In addition, I will show real-time pH-based control of bacteria motility and cardiomyocytic calcium signaling, providing insights into their dynamic responses to time-variable extracellular-pH modulations. Together, the unique capabilities of our graphene-enabled electronics open up new opportunities for high-performance sensing and modulation of complex biological systems across diverse spatiotemporal scales for both fundamental research and translational applications.