Objectives Immune reconstitution inflammatory syndrome (IRIS) is a major concern when starting antiretroviral therapy (ART) in patients with advanced HIV infection. The aim of this study was to determine the incidence and risk factors of IRIS in HIV‐infected Koreans initiating ART, and whether integrase strand transfer inhibitor (INSTI) treatment increases the risk of IRIS. Methods This retrospective analysis included adults living with HIV, seen at four university‐affiliated hospitals in South Korea, who were naïve to ART and had a CD4 T‐cell count < 200 cells/μL between January 2004 and May 2019. IRIS was determined through a medical record review within 6 months of ART initiation. Propensity score‐matched case–control study between the non‐INSTI and INSTI groups was performed. Results The study included 501 patients; 192 were assigned to the INSTI group, who started ART based on INSTIs as the initial treatment. There were opportunistic infections (OIs) in 253 (50.5%) cases before ART initiation. The three most common OIs were Pneumocystis jirovecii pneumonia, candidiasis and tuberculosis (TB). We identified 47 cases of IRIS; TB‐IRIS was the most common type. The incidence of IRIS within 6 months of ART initiation was 9.4%, and there were no significant differences in baseline characteristics and incidence of IRIS between the matched groups. The risk factors for IRIS were pre‐ART CD4 T‐cell count (< 30 cells/μL), higher pre‐ART viral load (≥ 75 000 copies/mL), and TB‐OI. Conclusions The incidence of IRIS was 9.4% in Korean HIV patients. The INSTI regimen was not related to IRIS occurrence.