Transient electronics have emerged as a new category of devices that can degrade after their functional lifetime, offering tremendous potential as disposable sensors, actuators, wearables, and implants. Additive manufacturing methods represent a promising approach for patterning transient materials, yet examples of fully printed bioelectronic devices are scarce. This study introduces a fully digital 3D printing approach enabling the prototyping and customization of soft bioelectronics made of transient materials. The direct ink writing of poly(octamethylene maleate (anhydride) citrate) (POMaC) as an elastomeric matrix and of a shellac-carbon ink as a conductor is investigated. Precise and repeatable deposition of both structural and conductive features is achieved by optimizing printing parameters, i.e., the dispense gap, printing speed, and inlet pressure. Multi-material 3D printing enables the fabrication of functional transient devices. Notably, pressure and strain sensors are shown to operate in ranges relevant to implanted biomechanical monitoring. 3D-printed transient electrodes are demonstrated to be comparable to state-of-the-art devices in terms of impedance behavior. Finally, physical degradation of the materials is confirmed at physiological conditions. These fully digital additive manufacturing processes enable the monolithic fabrication of customizable transient bioelectronics with adaptable functions and geometries.