Background The efficacy and toxicity of KRAS(G12C) inhibitors were evaluated for advanced solid tumors in several studies; however, the results were not fully consistent. Methods Clinical trials evaluating KRAS(G12C) inhibitors for advanced solid tumors were searched from PubMed, Embase, and Cochrane Library online databases up to 31st December 2023. The characteristics of the studies and the results of objective response rate (ORR), disease control rate (DCR), duration of response (DoR), progression-free survival (PFS) rate, overall survival (OS) rate, and treatment-related adverse events (trAEs) were extracted. Results Ten studies with 925 heavily pretreated advanced patients harboring KRAS(G12C) mutation were included. For total population, the pooled analysis of ORR was 28.6% (95%CI, 21.2-36.6%), DCR was 85.5% (95%CI, 82.2-88.6%), PFS rate at 6 months (PFS6) was 49.6% (95%CI, 41.4-57.9%), PFS rate at 12 months (PFS12) was 26.7% (95%CI, 19.8-34.1%), OS rates at 6 months (OS6) was 76.2% (95%CI, 68.8-82.9%), OS rates at 12 months (OS12) was 47.8% (95%CI, 38.6-57.0%). The pooled analysis of any grade trAEs was 79.3% (95%CI, 66.2-90.0%) and grade three or more trAEs was 24.4% (95%CI, 16.7-32.9%). The median time to response and DoR results from individual data were 1.39 months (95%CI, 1.37-1.41 months) and 10.54 months (95%CI, 7.72-13.36 months). Sotorasib had significantly lower pooled incidences of any trAEs (OR, 0.07, 95%CI, 0.03-0.14) and grade three or more trAES (OR, 0.34, 95%CI, 0.24-0.49) compared with adagrasib. Conclusions KRAS(G12C) inhibitors have good ORR, DCR, PFS rate, OS rate, tolerable trAEs, and early response with long duration in advanced solid tumors; however, most of the pooled results were heterogeneous. Sotorasib has shown better safety results.