Kidney organoids, derived from stem cells, including pluripotent stem cells and adult progenitor cells, have been reported as three-dimensional in vitro models that reflect key aspects of kidney development, structure, and function. Advances in differentiation protocols and tissue engineering have enabled the generation of organoids that exhibit nephron-like structures, including glomerular and tubular structures. Kidney organoids have been widely applied in several directions, including disease modeling and therapeutic screening, drug nephrotoxicity evaluation, and regenerative medicine. In particular, kidney organoids offer a promising platform for studying genetic kidney diseases, such as polycystic kidney disease and congenital anomalies of the kidney and urinary tract (CAKUT), by allowing patient-specific modeling for the analysis of pathophysiology and therapeutic screening. Despite several current limitations, such as incomplete maturation, lack of full nephron segmentation, and variability between protocols and cell conditions, further technological innovations such as microfluidics and bioengineering may refine kidney organoid systems. This review highlights recent advances in kidney organoid research, outlines major applications, and discusses future directions to enhance their physiological relevance, functional maturity, and translational integration into preclinical and clinical nephrology.