Herein, a new and facile synthesis of a tin-carbon nanocomposite and its electrochemical characterization is presented. Tin nanoparticles were embedded in micron-sized carbonaceous particles, thus successfully preventing the aggregation of tin nanoparticles and buffering the occurring volume strain, which accompanies the reversible (de-)alloying process. Such active material presents specific capacities of around 440 and 390mAhg−1 for applied specific currents of 0.1 and 0.2Ag−1, respectively, as lithium-ion anode using environmentally friendly and cost-efficient carboxymethyl cellulose as binder. Even more remarkably, at very high specific currents of 2, 5, and 10Ag−1, electrodes based on this composite still offer specific capacities of about 280, 240, and 187mAhg−1, respectively. In addition, this tin-carbon nanocomposite appears highly promising as anode material for sodium-ion batteries, showing very stable cycling performance in a suitable potential range, and specific capacities of more than 180, 150, 130, and 90mAhg−1 for an applied specific current of 12.2, 122, 244, and 610mAg−1, respectively, thus highlighting the high versatility of this composite active material for both Li-ion and Na-ion battery technologies.