OBJECTIVE These post hoc analyses of the Semaglutide Treatment Effect in People with obesity (STEP) 1–3 trials (NCT03548935, NCT03552757, and NCT03611582) explored the effects of semaglutide (up to 2.4 mg) on kidney function. RESEARCH DESIGN AND METHODS STEP 1–3 included adults with overweight/obesity; STEP 2 patients also had type 2 diabetes. Participants received once-weekly subcutaneous semaglutide 1.0 mg (STEP 2 only), 2.4 mg, or placebo for 68 weeks, plus lifestyle intervention (STEP 1 and 2) or intensive behavioral therapy (STEP 3). Changes in urine albumin-to-creatinine ratio (UACR) and UACR status from baseline to week 68 were assessed for STEP 2. Changes in estimated glomerular filtration rate (eGFR) were assessed from pooled STEP 1–3 data. RESULTS In STEP 2, 1,205 (99.6% total cohort) patients had UACR data; geometric mean baseline UACR was 13.7, 12.5, and 13.2 mg/g with semaglutide 1.0 mg, 2.4 mg, and placebo, respectively. At week 68, UACR changes were 214.8% and 220.6% with semaglutide 1.0 mg and 2.4 mg, respectively, and +18.3% with placebo (be-tween-group differences [95% CI] vs. placebo: 228.0% [237.3, 217.3], P < 0.0001 for semaglutide 1.0 mg; 232.9% [241.6, 223.0], P = 0.003 for semaglu-tide 2.4 mg). UACR status improved in greater proportions of patients with sema-glutide 1.0 mg and 2.4 mg versus placebo (P = 0.0004 and P = 0.0014, respectively). In the pooled STEP 1–3 analyses, 3,379 participants had eGFR data; there was no difference between semaglutide 2.4 mg and placebo in eGFR trajectories at week 68. CONCLUSIONS Semaglutide improved UACR in adults with overweight/obesity and type 2 diabe-tes. In participants with normal kidney function, semaglutide did not have an effect on eGFR decline.