Cerebellar hemorrhage (CH) is considered a predictive factor for poor outcome after intracranial hemorrhage because of the high risk of brainstem compression. Hence, predictors of early mortality in patients with spontaneous CH are clinically valuable. However, the predictors of death within 7 days of CH onset have not yet been studied. In this study, 70 patients with acute spontaneous CH were retrospectively analyzed. The patients were divided into the first-week mortality group (n = 15, died within 7 days) and survival group (n = 55, survived at discharge). The association between first-week mortality and clinical characteristics was investigated using a multivariate logistic regression. The initial Glasgow coma scale (GCS) values (5.0 ± 2.8) in the first-week mortality group were significantly lower than those in the survival group (12.8 ± 3.3) (p < 0.001). Brainstem compression was indicative of first-week mortality (p < 0.001). GCS scores ≤8 (odds ratio, OR = 32.344, p = 0.003) and brainstem compression (OR = 14.417, p = 0.009) were strong predictors of first-week mortality in patients with CH. This is the first study showing that GCS scores ≤8 on arrival and brainstem compression are strong predictive factors for first-week mortality in patients with CH. These patients were about 32 and 14.5 times, respectively, more likely to die within 7 days.