Key Points We identified four kidney function trajectories in ANCA-associated vasculitis associated with varied risk of ESKD and CKD. Male sex, myeloperoxidase-ANCA specificity, baseline hypertension, and lower baseline eGFR were associated with adverse kidney function trajectory. Differences in baseline characteristics identify potential targets for personalized care. Background ANCA-associated vasculitis (AAV) causes GN culminating in a spectrum of CKD and ESKD. Kidney function trajectories with differing CKD risk were reported in a single-center study. We sought to confirm these findings in the Plasma Exchange and Glucocorticoids in Severe AAV trial cohort. Methods This cohort study included patients from Plasma Exchange and Glucocorticoids in Severe AAV with a baseline and one or more eGFR measurements over 36 months to identify groups with similar longitudinal change in kidney function using group-based trajectory analysis. We evaluated factors associated with group membership using multivariable-adjusted multinomial logistic regression. Results We identified four trajectory groups among 663 patients: early ESKD (113, 17%), stable impairment (400, 60%), impaired with improvement (131, 20%), and marked improvement (19, 3%). ESKD occurred in 137 patients (21%): 113 (100%) in the early ESKD, 23 (6%) in the stable impairment, and 1 (1%) in the impaired with improvement groups. Older baseline age (adjusted odds ratio [aOR], 0.97 per 1 year; 95% confidence interval [CI], 0.95 to 0.99), female sex (aOR, 0.54; 95% CI, 0.31 to 0.94), and baseline eGFR (aOR, 0.93 per 1 ml/min per 1.73 m 2 increase; 95% CI, 0.88 to 0.99) were associated with lower odds of early ESKD versus impaired with improvement membership. Myeloperoxidase-ANCA+ (aOR, 2.35; 95% CI, 1.33 to 4.16) and hypertension (aOR, 2.50; 95% CI, 1.33 to 4.69) were associated with higher odds of early ESKD membership. Conclusions We identified four kidney function trajectories in AAV associated with varied risk of ESKD and CKD; male sex, myeloperoxidase-ANCA specificity, baseline hypertension, and lower baseline eGFR were associated with adverse kidney function trajectory. Differences in baseline characteristics identify potential targets for personalized care.