This presentation introduces various inkjet-/3D-printed flexible antennas, RF electronics, and microfluidic sensors for wearable applications. By using these additive manufacturing (AM) techniques, wearable devices with an excellent flexibility and an extremely low profile can be fabricated on-demand at a low cost. The problems and solutions of designing wearable antenna/RF electronics, including detuning effect, attenuation effect and shadowing effect will be discussed, along with the fabrication challenges for these devices with traditional fabrications methods and additive manufacturing techniques. To demonstrate the capability of recent AM techniques, the smallest microfluidics topology fabricated by AM would be introduced. Examples of inkjet-/3D-printed microfluidics sensor will be then presented, which can be used in microwave fluid sensing for wearable health monitoring and various Internet-of-Things (IoT) applications.