Yoga has been shown to have health benefits, whereas exercising in a hot environment has deleterious effects on kidney function. There are no long-term studies on the physiological effects of hot yoga. The purpose of this study was to investigate changes in renal function acutely and over time between practitioners of hot and non-hot yoga. Urine and capillary samples were collected for urinalysis, albumin-creatinine ratio, and serum creatinine at yoga studios preand postexercise over 1 year. Thirty-two participants in non-hot yoga and 19 participants in hot yoga were recruited. Difference in blood capillary creatinine (post-yoga minus pre-yoga) showed a 7.52 μmol/L (SD 11.46) increase for practitioners of hot yoga and a 4.07 μmol/L (SD 9.94) increase for practitioners of non-hot yoga, with a between-group difference of 3.45 μmol/L (95% CI −0.42, 7.32; p = 0.08). Over 1 year, the mean difference in blood capillary creatinine for the hot group increased by 0.91 μmol/L (SD 11.00) and by 3.08 μmol/L (SD 9.96) for the non-hot group, with a between-group difference of −2.17 μmol/L (95% CI −10.20, 5.86; p = 0.58). Over 1 year, the mean difference in albumin-creatinine ratio for the hot group was −0.16 mg/mmol creatinine (SD = 0.74); for the non-hot group the difference was −0.20 mg/μmol (SD = 0.80). The difference in difference between the hot and non-hot groups was 0.04 mg/μmol (95% CI −0.60, 0.68; p = 0.90). Urine collected for urinalysis could not be analyzed due to too many 0 values. This pragmatic observational study did not find a statistically significant change in renal function between participants in non-hot and hot yoga either acutely or over 1 year. A larger and longer study focusing on blood creatinine over time would help to inform the long-term effects of hot yoga on the kidneys.