The incorporation of ultrafine SnO2 particles inside N-doped ordered mesoporous carbon (N-CMK3) is suggested as a method to prepare an ultrastable anode material for Li-ion batteries. Sn nanoparticles formed by chemical reduction of SnCl4 inside N-CMK3 pores are spontaneously reoxidised by dissolved oxygen, resulting in the formation of ultrafine SnO2 inside N-CMK3 pores. This SnO2@N-CMK3 exhibits superior capacity, cyclability, and rate capability. Over 100 cycles at a rate of 0.1C, SnO2@N-CMK3 maintains a specific capacity of 635 mAh g−1, corresponding to a capacity retention of 86.6%. Over 1000 cycles at the rate of 0.5C, SnO2@N-CMK3 can deliver a capacity of 433 mAh g−1. At an ultrahigh rate of 5C, SnO2@N-CMK3 still delivers a capacity higher than that of commercial graphite. The full cell, composed of an SnO2@N-CMK3 anode, LiCoO2 cathode, and sacrificial Li electrode, presents excellent performance, better than previous reports of Li-ion cells. By employing a sacrificial Li electrode, the issue related to the low Coulombic efficiency of SnO2@N-CMK3 in the first few cycles and the pre-lithiation SnO2@N-CMK3 electrode can be successfully addressed.