Long-acting injectable antipsychotic agents (LAIs) including paliperidone palmitate (PP) have shown promising results in preventing relapse and rehospitalization in schizophrenia. This study aimed to ascertain the comparative real-world effectiveness between the early and late administration of PP and oral formulations of risperidone and paliperidone (ORPs) in patients experiencing a first episode or relapse of schizophrenia. We identified patients with schizophrenia admitted to a psychiatric ward at least once and treated with ORPs or PP using the Korea National Insurance Claims Database. Patients were divided into three groups based on the clinical data: (1) patients treated with PP within 30 days of the initiation of treatment (early-PP), (2) patients treated with PP after 30 days of the initiation of therapy (late-PP) and (3) patients treated with only ORPs and not received PP (only-ORP). The primary outcomes were determined as psychiatric rehospitalization during the entire duration of treatment after the first discharge. A total of 3790 patients (1096 early-PP, 799 late-PP and 1895 only-ORP) were finally included in the analysis. The mean of number and total length of rehospitalization stays during the entire duration in early-PP group were significantly lower than those of late-PP group and only-ORP group (number: 2.32 stays/year, 3.24 stays/year and 4.23 stays/year, p < .001; total length: 50.34 days/year, 72.26 days/year and 105.14 days/year, p < .001). Early treatment with PP was associated with a greater reduction in psychiatric rehospitalization during the treatment period than late treatment with PP and ORP in schizophrenia.