Metallic lithium (Li) anode batteries have attracted considerable attention due to their high energy density value. However, metallic Li is highly reactive and flammable, which makes Li anode batteries difficult to develop. In this work, for the first time, we report the synthesis of metallic Li-embedded carbon nanocomposites for easy and safe handling by a scalable ion beam-based method. We found that vertically standing conical Li-C nanocomposite (Li-C NC), sometimes with a nanofiber on top, can be grown on a graphite foil commonly used for the anodes of lithium-ion batteries. Metallic Li embedded inside the carbon matrix was found to be highly stable under ambient conditions, making transmission electron microscopy (TEM) characterization possible without any sophisticated inert gas-based sample fabrication apparatus. The developed ion beam-based fabrication technique was also extendable to the synthesis of stable Li-C NC films under ambient conditions. In fact, no significant loss of crystallinity or change in morphology of the Li-C film was observed when subjected to heating at 300 °C for 10 min. Thus, these ion-induced Li-C nanocomposites are concluded to be interesting as electrode materials for future Li-air batteries.