Lithium sulfur battery (LSB) is widely considered as a next-generation battery system due to its high theoretical energy density of 2567 Wh kg−1. However, several inherent issues obstruct the business application of LSB. To address these issues, we assemble core–shell structure Fe3O4@C nanodots with 5 nm diameter as a valid sulfur host via a convenient organic pyrolysis treatment followed by calcination. The nanosized Fe3O4 particles could expose more chemisorption sites and inhibit the polysulfides shuttle. Moreover, the carbon layer could not only increase the conductivity but also ensure structural integrity during cyclic process. Furthermore, the mesoporous channels around Fe3O4@C could supply sufficient space to load sulfur and physically restrict the shuttle of polysulfides. Thus, the resultant S/Fe3O4@C cathode shows a highly initial capacity of 1089 mAh g−1 at 0.2 C, even retains 655 mAh g−1 over 200 cycles at 1 C.