Purpose This meta-analysis was to critically evaluate the effects of aromatherapy on the symptoms of anxiety and depression in cancer patients. Methods Eight Chinese and English databases (CNKI, Wanfang, VIP, CBM, Cochrane Library, PubMed, Embase, and PsycINFO) were systematically searched from the inception of databases to October 2021 for randomized controlled trials (RCTs). According to Cochrane Collaboration criteria, two reviewers independently assessed the risk of bias and extract data from included studies. All analyses were performed with Review Manager 5.4. Results Eleven qualified studies were included in the meta-analysis, ten of which reported the effect of aromatherapy on anxiety in cancer patients, including 1724 patients; five of the studies reported the effect on depression, including 1039 patients. The quality of the included studies was low, and most studies compared aromatherapy to usual care. This meta-analysis indicated that aromatherapy appeared to be effective for anxiety [SMD = -0.51, 95%CI (−0.83, −0.19), P = 0.002] and depression [SMD = -0.44, 95%CI (−0.76, −0.12), P = 0.008] symptoms in cancer patients. Inhalation aromatherapy may be more effective than massage. Aromatherapy seemed to improve the anxiety symptoms in cancer patients in a short time, especially in perioperative patients, but had no effect for patients treated with radiation, chemotherapy or palliative therapy. Placebo also appeared to be effective in some studies. Conclusions Aromatherapy, especially inhalation aromatherapy, may help relieve symptoms of anxiety and depression in cancer patients, but more and higher-quality studies are needed. The literature does not yet support clinical implementation.