A wearable health monitoring system is a promising device for opening the era of the fourth industrial revolution due to increasing interest in health among modern people. Wearable health monitoring systems were demonstrated by several researchers, but still have critical issues of low performance, inefficient and complex fabrication processes. Here, we present the world's first wearable multifunctional health monitoring system based on flash‐induced porous graphene (FPG). FPG was efficiently synthesized via flash lamp, resulting in a large area in four milliseconds. Moreover, to demonstrate the sensing performance of FPG, a wearable multifunctional health monitoring system was fabricated onto a single substrate. A carbon nanotube‐polydimethylsiloxane (CNT‐PDMS) nanocomposite electrode was successfully formed on the uneven FPG surface using screen printing. The performance of the FPG‐based wearable multifunctional health monitoring system was enhanced by the large surface area of the 3D‐porous structure FPG. Finally, the FPG‐based wearable multifunctional health monitoring system effectively detected motion, skin temperature, and sweat with a strain GF of 2564.38, a linear thermal response of 0.98 Ω °C −1 under the skin temperature range, and a low ion detection limit of 10 μ m .