Biomarkers, defined as molecules in biological samples that are used as indicators of organ function, can assess exposure to potentially injurious chemicals, effects on organ function, or susceptibility to organ functional decline. The kidneys are frequently exposed to many drugs and chemicals and loss of kidney function is a frequent consequence of diseases such as diabetes. This review summarizes findings reported in 2021 and early-2022 from clinical and experimental animal studies on biomarkers, focusing on five topics: 1) Progression and severity of diabetic kidney disease; 2) acute kidney injury (AKI) and chronic kidney disease (CKD) severity and prognosis; 3) progression of AKI to CKD; 4) renal cell carcinoma (RCC) severity and prognosis; and 5) detection of exposure to environmental chemicals and nephrotoxic drugs.