A stability-indicating RP-HPLC method was developed and validated for the simultaneous estimation of Xanomeline (XAE) and Trospium chloride (TRC) in bulk and pharmaceutical formulations. Chromatographic separation was achieved on a C18 column using a mobile phase of acetonitrile and heptane sulfonic acid buffer (pH 2.5) in a 20:80 (v/v) ratio, with PDA detection at 231 nm. The method demonstrated good system suitability with acceptable resolution, theoretical plate counts (> 2000), and tailing factors. Validation in accordance with ICH guidelines confirmed excellent precision (%RSD < 2), accuracy, robustness, and reproducibility, supporting its suitability for routine quality control and stability studies. The forced degradation study demonstrates that the analyte exhibits acceptable stability under a range of stress conditions, including acid, alkali, peroxide, reduction, thermal, photolytic, and hydrolytic environments. Compared to the control sample (100% assay), degradation varied from minimal to moderate depending on the stress applied. In all stress conditions, peak purity parameters remained within acceptable limits, confirming the stability-indicating capability of the method.