Malaria is known to be a significant risk factor and also a potential complicating factor during the treatment of lymphoid malignancy. There has not been a reported case of malaria reactivation that occurred weeks after cytotoxic chemotherapy completion, especially in non-endemic regions. Our patient was a 47-year-old man with a history of repeated falciparum malaria infection experiencing 2 months of progressive unilateral nasal blockage and recurrent anterior epistaxis, which was diagnosed as diffuse large B-cell lymphoma (DLBCL) through pathological examination. He was treated with six cycles of classical R-CHOP, resulting in complete remission. One month after remission, he experienced shivering, fever, sweating, and a return to normal temperature, which repeated irregularly for roughly 1 week. His laboratory result showed anaemia, leucopenia, and profound thrombocytopenia. Immunochromatographic testing (ICT) confirmed the diagnosis of falciparum malaria. This case was considered a relapse since our centre is not in the malaria-endemic region. He was cured with a combination of dihydroartemisinin-piperaquine and primaquine. Our case demonstrated the duality of malaria as potential aetiology and treatment complicating factor in DLBCL.