Baricitinib is a novel therapeutic agent recently approved for the treatment of moderate to severe rheumatoid arthritis, severe alopecia areata, and since 2022, COVID-19 in hospitalized adults requiring supplemental oxygen. This drug acts as a selective inhibitor of Janus kinase 1 and 2. This study aimed to establish and validate a stability-indicating UV spectroscopic method for the measurement of baricitinib in both bulk and formulated forms. A straightforward, precise, and cost-effective UV method was developed using dimethylformamide (DMF) and distilled water as the solvent. To prepare the standard stock solution, 10 mg of baricitinib was dissolved in 1 mL of DMF and then diluted with distilled water. Subsequent dilutions were prepared using distilled water and analyzed at a wavelength of 309 nm. The validation of this method was performed according to ICH Q2 R(2) guidelines. The method demonstrated linearity in the concentration range of 10-100 μg/mL with an excellent correlation coefficient (r² = 0.999). The precision results were within the acceptable range, and the % RSD was less than 2.0. Therefore, this developed method is reliable, sensitive, and reproducible, making it suitable for routine quality control analysis of baricitinib.