Total globulin fraction (TGF) is calculated by subtracting serum albumin levels from serum total protein levels. The present study examined whether TGF at diagnosis could forecast all-cause mortality during the disease course in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The present study included 283 patients with AAV. The variables at AAV diagnosis such as demographic data, AAV-specific data including the Birmingham vasculitis activity score (BVAS), five-factor score (FFS), and laboratory data including ANCA, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were collected. The number of deceased patients during the follow-up duration based on all-cause mortality was counted. The median age of the 283 AAV patients was 60 years, and 35.7% were men. ANCAs were detected in 228 patients, and the median TGF was 2.9. A total of 39 patients (13.8%) died within a median follow-up duration of 46.9 months. TGF at AAV diagnosis was significantly correlated with ESR and CRP rather than AAV activity. Patients with ANCA positivity exhibited a significantly higher median TGF at AAV diagnosis than those without. Patients with TGF ≥ 3.1 g/dL at AAV diagnosis exhibited a significantly lower cumulative survival rate than those without. Furthermore, in the multivariable Cox hazards model analysis, TGF ≥ 3.1 g/dL (hazard ratio 2.611) was independently associated with all-cause mortality, along with age, male sex, and body mass index. The present study is the first to demonstrate that TGF at AAV diagnosis can forecast all-cause mortality during the disease course in AAV patients.