ObjectiveThis study aimed to evaluate the effectiveness of web‐based interventions in depression and anxiety among informal caregivers of patients with cancer.MethodsDatabases such as PubMed, Cochrane, Web of Science, Embase, CINAHL, and PsycINFO were systematically searched from inception to April 15, 2024. Eligible studies encompassed randomized controlled trials (RCTs) focusing on web‐based interventions tailored to informal caregivers of patients with cancer. The effect size was calculated as the standardized mean difference (SMD) with a 95% confidence interval (CI) utilizing a random effects model. The risk of bias was assessed independently utilizing Cochrane's Risk of Bias Tool (version 2.0) for RCTs.ResultsA total of 12 RCTs were incorporated into this meta‐analysis. Web‐based interventions demonstrated a significant effect in ameliorating depression among informal caregivers of patients with cancer compared to the control group (SMD = −0.21, 95% CI = −0.36 to −0.05, p < 0.01, I2 = 15%). Additionally, a significant effect was also observed in alleviating anxiety (SMD = −0.20, 95% CI = −0.36 to −0.05, p = 0.77, I2 = 0%).ConclusionsWeb‐based interventions might be effective in reducing depression and anxiety among informal caregivers of patients with cancer. Nevertheless, several studies with an overall high risk of bias were included. As a result of the limited number and heterogeneity of the studies included in the subgroup analysis, deriving definitive conclusions on the most effective intervention components was challenging. Therefore, further studies incorporating high‐quality research are warranted.