To evaluate the characterization of Famotidine API (active pharmaceutical ingredient) and develop the accurate, precise, linear ultra-performance liquid chromatographic (UPLC) method for quantitating determination of organic impurities (Impurity-A, Impurity-B, and Impurity-C) in Famotidine API, pharmaceutical dosage forms and the method has been validated as per international council of harmonization (ICH) guidelines. The Famotidine API characterization was done by using spectroscopic techniques such as mass, infrared spectroscopy (IR), differential scanning calorimetry (DSC), proton nuclear magnetic resonance (1H-NMR), Carbon-13 nuclear magnetic resonance (C13-NMR), and two-dimensional nuclear magnetic resonance (2D-NMR). The organic impurities (A, B, and C) quantification was done using ACQUITY UPLC CSH C18- 100 mm × 2.1 mm, 1.7 μm column connected to ACQUITY UPLC with PDA detector. The optimized chromatographic conditions were achieved at 0.3 mL/min flow rate using a gradient system with 0.1% Tri fluoro acetic acid in water acetonitrile and Methanol as mobile phase. Three organic impurities are measured at λmax 260 nm at 45°C column temperature. Famotidine structure was confirmed by the appraised complete characterization data. The coefficient of correlation (r2) for the Impurity-A, Impurity-B, and Impurity-C was obtained not less than 0.99. The limit of detection (LOD) obtained 0.12 µg/mL and the limit of quantification (LOQ) obtained 0.4 µg/mL for each impurity concerning Famotidine test concentration. The method was fully validated as precision, accuracy, LOQ precision, LOQ accuracy, ruggedness, and robustness complying with FDA, ICH, AOAC, and European medicines agency (EMEA) guidelines. The characterization study and the proposed UPLC method were specific, accurate, precise, linear, rugged, and robust for the determination of the three organic impurities in Famotidine API and it can be implemented for its intended use in pharmaceutical industries.