We demonstrated a first-principles investigation to search for magnetic superatoms in the vanadium-doped lithium clusters VLi(n) (n = 1-13). The stabilities of VLi(n) clusters were determined through geometrical and electronic optimizations. It is found that the growth pattern of VLi(n) in 3-space follows adding a Li atom capped on VLi(n-1) clusters. All doped clusters show larger relative binding energies compared with pure Li(n+1) partners and display tunable magnetic properties. When n = 8-13, the VLi(n) clusters adopt a cage-like structure with an endohedral V atom and are identified as superatoms with their magnetic moments successively decreasing from 5 to 0 μB. The isolated VLi8 superatom is emphasized due to its robust magnetic moment as well as high structural and chemical stability analogue of a single Mn(2+) ion. Molecular orbitals analysis shows that VLi8 has an electronic configuration of 1S(2)1P(6)1D(5), exhibiting Hund's filling rule of maximizing the spin-like atoms. Electronic shell structures of 1S(2) and 1P(6) are virtually unchanged in Li9 cluster as the V atom substitutes for the embedded Li atom, indicating that the electron-shell-closing model is valid for explaining its structures and stabilities. The results show that the tailored magnetic building blocks for nanomaterials can be formed by seeding magnetic dopants into alkali metal cluster cages.