Abstract Background The future of combined immunotherapy (a PD-1/PD-L1 plus a CTLA-4 antagonist) is very bright. However, besides improving efficacy, combined therapy increases treatment-related adverse events (TRAEs). Also, the clinical application is limited in some solid tumors. Methods This paper purports to investigate the TRAEs for the combined immunotherapy aiming for a more appropriate utilization of immune checkpoint inhibitors (ICIs) in clinical practice through a meta-analysis. Results A total of 17 eligible studies covering 2626 patients were selected for a meta-analysis based on specified inclusion and exclusion criteria. The incidence rates of any grade and grade 3 or higher TRAEs were 88% (95%CI, 84–92%) and 41% (95%CI, 35–47%), respectively. The overall incidence of any grade TRAEs leading to discontinuation of treatment was 20% (95%CI, 16–24%). The incidence rate of treatment related deaths was 4.3‰ (95%CI, 1.4‰-8.4‰). Analysis showed that NIVO1 + IPI3 cohort had higher incidences of grade 3 or higher TRAEs (RR = 1.77, 95%CI, 1.34–2.34, p