BACKGROUND/OBJECTIVES: Janus kinase inhibitors open new horizons for small-molecule drugs in treating inflammatory bowel disease, with ritlecitinib demonstrating significant efficacy in clinical trials for ulcerative colitis and Crohn's disease. Ritlecitinib, a second-generation JAK3 inhibitor, is a novel therapeutic agent for alopecia areata and other autoimmune conditions. METHODS: A new stability-indicating UHPLC-DAD-MS/MS method was developed, validated, and applied for a forced degradation study of ritlecitinib under ICH guidelines. RESULTS: The method demonstrated high specificity, sensitivity (LOD: 0.04 microg/mL; LOQ: 0.14 microg/mL), precision (RSD </= 0.15%), and accuracy (99.9-100.3%). Forced degradation studies under acidic, basic, oxidative, thermal, and photolytic conditions revealed four novel degradation products. Basic degradation followed second-order kinetics, while oxidative degradation followed zero-order kinetics. CONCLUSIONS: The validated method reliably characterized ritlecitinib's stability and degradation products, providing essential data for optimizing formulation, determining proper storage conditions, anticipating drug-excipient interactions, and ensuring quality control. The eco-friendliness and applicability of the developed forced degradation procedure were evaluated using various green and blue metric tools. Incorporating green analytical principles underscores its potential for sustainable pharmaceutical analysis.