The interweaving of functional materials with multiscale smart 3D-printing processes could enable the additive manufacturing of a diverse set of complex, flexible, multifunctional devices. To this end, the focus of this research is to introduce the 3D-printing of artificial organs, wearable biosensors, flexible electronics, biomimetic devices, and soft robots with unique geometries and extraordinary functionalities that can be utilized for biomedical and engineering applications. Firstly, 3D printed, patient-specific artificial organs with physical properties of tissue and integrated tactile sensors will be presented and their applications in surgical rehearsal and device evaluation will be discussed. Secondly, 3D-printed wearable biosensors and flexible electronics using customized materials will be introduced. These sensors can be used for health monitoring and motion detection. Finally, 3D-printed biomimetic devices and soft robots will be introduced. These devices with enhanced locomotion performance can be applied for ground and underwater applications.