Maintaining the thermal comfort of human bodies in hot weather is one of the most basic needs for life and is generally achieved with external active devices, such as air conditioners and fans. The utilization of these electricity-powered devices usually costs a considerable amount of energy. We have developed a novel wearable patch that can cool human bodies in the daytime without needing electricity. The patch has judiciously engineered multiscale porous structures. It can reflect sunlight efficiently and will not be heated up. Meanwhile, human bodies can still dissipate heat through the patch, so the heat produced by human bodies won’t be trapped underneath. As a result, the patch-covered body areas exhibit around 11 degrees Fahrenheit lower than the exposed skin. In addition, we have patterned multimodal biomedical devices on the wearable patch, which can monitor a rich variety of vital physiological signals (e.g., body temperatures, skin hydration levels, EKG, heart rates, glucose levels) from human bodies. Thus, the patch can also be used for the early diagnosis of various diseases and adverse conditions and will facilitate home-centered, personalized human healthcare.