<p>Amino acids are the building blocks of protein synthesis and play important roles in the generation of adenosine triphosphate (ATP), glucose, and fatty acids as metabolic precursors. Consequently, they serve as both structural components and energy sources for cells, supporting growth, differentiation, and function. Metabolic disorders involving amino acids have been associated with multiple clinical pathologies, including diabetic kidney disease (DKD). Increasing evidence suggests that amino acid metabolic pathways may act as novel contributors to the development of DKD. Thus, a deeper understanding of amino acid metabolism in DKD and the identification of key targets within amino acid metabolic pathways may facilitate the development of novel therapeutic strategies. To this end, this review focuses on three representative pathways—branched-chain amino acids, urea-cycle-related amino acids, and carnitine metabolism—that have emerged as key contributors to DKD progression, and discusses the advantages, limitations, and future directions of cell-specific therapeutic strategies.</p>