Objective: We assessed the relationship of body weight time in target range (TTR) with composite kidney outcome in people with overweight/obesity and type 2 diabetes mellitus (T2DM). Research design and methods: Included in this study were 3,601 participants with baseline estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 from the Look AHEAD (Action for Health in Diabetes) trial. Body weight TTR was defined as the proportion of time during the first 4 years that body weight was within the weight loss target (a weight loss of ≥7% from baseline). The primary outcome was composite kidney outcome, defined as eGFR decline ≥30% from baseline and to a level <60 mL/min/1.73 m2 at follow-up visit, or end-stage kidney disease. Results: During a median follow-up of 8.0 years, 435 cases of composite kidney outcome were documented. Body weight TTR during the first 4 years was inversely associated with the subsequent risk of composite kidney outcome (per SD increment; adjusted hazard ratio [HR] 0.81; 95% CI 0.70-0.93). Accordingly, the adjusted HRs (95% CI) of composite kidney outcome were 1.00 (reference), 0.73 (0.54-1.00), 0.71 (0.52-0.99), and 0.54 (0.36-0.80) for participants with body weight TTR of 0%, >0% to <29.9%, 29.9% to <69.7%, and 69.7% to <100%, respectively. Similar results were found for a doubling of the urine albumin to creatinine ratio (secondary outcome). Conclusions: A higher body weight TTR, with a weight loss target of losing ≥7% of initial weight, was associated with a lower risk of kidney outcomes in participants with overweight/obesity and T2DM.