Detection of liquid viscosity is important from chemical engineering to daily safety. To match the emergence of internet of things, precise and fast viscosity determination is attracting intention in the society. However, most miniature viscometers face limitations such as high operation frequency, moving component, and non‐linear sensing, etc. Herein, a flexible viscometer is developed via coupling the electromagnetic induction with inherent oscillation of a magnetized oscillator. The mechanism allows vibration of the oscillator to be electrically reflected using damping signals. By analyzing the damping factor from viscosity‐dependent voltage profiles, viscosity of an unknown liquid can be accurately obtained. Furthermore, the 3D structures is developed with a dual‐template method, which enables convenient and high‐throughput preparations of devices with complex 3D structures. Via optimizing the structural and …