BACKGROUND Sodium-glucose co-transporter 2 inhibitor (SGLT2i) has been shown to improve renal outcomes in both diabetic and non-diabetic kidney disease. However, the effect of SGLT2i on renal outcomes in patients with non-diabetic obesity is still not established. METHODS In this double-blind, randomized controlled trial, we assigned non-diabetic patients with body mass index (BMI) ≥ 25 kg/m2, persistent 24-hour urine albumin-creatinine ratio (UACR) ≥ 10 mg/gCr, and estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73m2, who had been treated with renin-angiotensin system blockade, to canagliflozin 100 mg daily or placebo for 24 weeks. The reduction in UACR and eGFR at 12 and 24 weeks were explored. (Thai Clinical Trials Registry 20190203003). RESULTS Of 247 non-diabetic obese patients screened, 32 patients met inclusion criteria and underwent randomization. The median baseline of UACR was 69.1 mg/gCr. There were no statistically significant differences in albuminuria reduction between the groups at 12 weeks and 24 weeks. The estimated GFR in the canagliflozin group decreased significantly from baseline at 12 weeks (-5.39 mL/min/1.73m2; 95% CI -9.81 to -0.97; p = 0.017) but not at 24 weeks (-1.16 mL/min/1.73m2; 95% CI -5.58 to 3.26; p = 0.66), and there was no significant change from baseline in the placebo group at both 12 and 24 weeks. CONCLUSIONS Canagliflozin 100 mg daily was well tolerated but did not significantly reduce UACR in non-diabetic obese patients with microalbuminuria. However, a significant temporary decline in eGFR might reflect a subtle reduction in glomerular hyperfiltration.