3D objects with integrated electronics were produced using an additive manufacturing approach relying on multiphoton fabrication (direct laser writing, DLW). Conducting polymer-based structures (with micrometer-millimeter scale features) were printed within exemplar matrices, including an elastomer (polydimethylsiloxane, PDMS) widely investigated for biomedical applications. The fidelity of the printing process in PDMS was assessed by optical coherence tomography, and the conducting polymer structures were demonstrated to be capable of stimulating mouse brain tissue in vitro. Furthermore, the applicability of the approach to printing structures in vivo was demonstrated in live nematodes (Caenorhabditis elegans). These results highlight the potential for such additive manufacturing approaches to produce next-generation advanced material technologies, notably integrated electronics for technical and medical applications (e.g., human-computer interfaces).