Aims To explore the benefits of curative treatments (liver resection or local ablation) combined with splenectomy for patients with hepatocellular carcinoma (HCC) and Child grade B liver function. Methods We reviewed 245 patients with Child grade B liver function who underwent treatment with curative intent for HCC. Among these patients, 116 patients underwent curative treatment combined with splenectomy (the splenectomy group); the other 129 patients only underwent curative treatment (the non-splenectomy group). A one-to-one matching produced 95 paired patients, perioperative and oncological outcomes were compared, and liver function changes were reassessed 1 year later. Results The perioperative liver failure rates were 7.4% and 6.3% (P = 1.000) and the 90-day mortality was 4.2% and 6.3% (P = 0.747) in the splenectomy group and non-splenectomy group, respectively. The 1-, 3-, and 5-year overall survival rates were remarkably greater in the splenectomy group than in the non-splenectomy group (92.6% vs. 79.8%, 53.4% vs. 34.7%, and 19.9% vs. 11.0%, respectively; P = 0.004). In the univariate and multivariate analyses, splenectomy was identified as a protective factor for long-term survival. The proportion of patients whose liver function improved to Child A 1 year after surgery was also higher in the splenectomy group than in the non-splenectomy group (95.4% vs. 83.3%; P = 0.048). Conclusions Compared with non-splenectomy, curative treatments combined with splenectomy for patients with HCC and Child B grade liver function showed no different perioperative outcomes but achieved significant survival benefit. Splenectomy is a beneficial factor for patients with HCC and Child B liver function; liver function improved significantly 1 year after splenectomy.