This trial analyzed high-sensitivity C-reactive protein (hs-CRP), homocysteine (Hcy), and macrophage migration inhibitory factor (MIF) level in serum and their correlation with symptom severity and cognitive function in patients with schizophrenia (SP). Sixty-eight SP patients were enrolled in the SP group, and 68 healthy volunteers were in the control (CN) group. Serum hs-CRP, Hcy, and MIF were measured, and symptom severity was assessed with the Positive and Negative Symptom Scale (PANSS). Cognitive function was determined with the MATRICS Consensus Cognitive Battery (MCCB). The SP group was divided into high PANSS score (PANSS ≥70 points) and low PANSS score (PANSS <70 points), or the mild cognitive dysfunction group and severe cognitive dysfunction group according to the median MCCB score. The correlation between serum hs-CRP, Hcy, and MIF levels and PANSS and MCCB scores in SP patients was examined by Pearson correlation analysis. SP patients had higher serum hs-CRP, Hcy, and MIF levels and showed higher PANSS scores and lower MCCB total score. Serum hs-CRP, Hcy, and MIF levels in the high PANSS group were higher than those in the low PANSS group and in the severe cognitive dysfunction group than in the mild cognitive dysfunction group. Serum hs-CRP, Hcy, and MIF levels in SP patients were positively correlated with PANSS total score and negatively correlated with MCCB total score. High serum hs-CRP, Hcy, and MIF levels in SP patients are correlated with symptom severity and cognitive dysfunction.