The past two decades have witnessed an explosion in lab-on-a-chip research with applications in biology, chemistry, and medicine. Recently, a new lab-on-a-chip frontier has emerged, joining acoustics with microfluidics, termed acoustofluidics. Here, we summarize our recent progress in this exciting field and show the depth and breadth of acoustofluidic tools for biomedical applications through many unique examples, including exosome separation, cell-cell communication studies, three-dimensional bioprinting, circulating tumor cell isolation and detection, ultra-high-throughput blood cell separation, high-precision micro-flow cytometry, and portable fluid manipulation systems. These acoustofluidic technologies are capable of delivering high-precision, high-throughput, and high-efficiency cell/particle/fluid manipulation in a simple, inexpensive, cell-phone-sized device. More importantly, the acoustic power intensity and frequency used in these acoustofluidic devices are in a similar range as those used in ultrasonic imaging, which has proven to be extremely safe for health monitoring during various stages of pregnancy. As a result, these methods are extremely biocompatible, i.e., cells and other biospecimens can maintain their natural states without any adverse effects from the acoustic manipulation process. With these advantages, acoustofluidic technologies meet a crucial need for highly accurate disease diagnostics (e.g., early cancer detection and monitoring of prenatal health) and effective therapy (e.g., transfusion and immunotherapy).