Cathode material is not only a crucial component of lithium iron phosphate batteries (LFP or LiFePO4) but is also ideally qualified for its low cost, non-toxicity, safety characteristics, and environmental friendliness. This work therefore aims to improve the cathode material efficiency for LiFePO4. A microwave-assisted solid-state method with chitin (shrimp shell waste), an organic carbon source, was used to synthesize cathode materials for LiFePO4 (LFPM). The results revealed that the carbon element in the chitin-coated LFPM material is 19.80 wt%, which can be homogeneously mixed and has an average particle size of ∼380 nm. The optimal time for the synthesis of the LFPM cathode material by the microwave-assisted solid-state method is 5 minutes, resulting in a phase that is pure, high-quality crystalline, and has the greatest electrical conductivity. Regarding the electrochemical performance, the initial charge and discharge capacities were 112.09 and 112.11 mAh/g, respectively, and the columbic efficiency was 99.97% over 20 cycles. The initial energy density was 336.68 Wh/kg. It can be concluded that the cathode material for LiFePO4 synthesized by the microwave-assisted solid-state method, coated with carbon derived from chitin, has good electrical performance, can be manufactured on a large scale, and is commercially feasible.