Recently, men with overactive bladder have been prescribed mirabegron and tamsulosin for the treatment of benign prostatic hyperplasia. Highly efficient and environmentally sustainable spectrophotometric methods have been developed for the accurate determination of mirabegron and tamsulosin in their pure forms as well as within pharmaceutical formulations. This study presents three effective and simple spectrophotometric methods for the simultaneous quantification of mirabegron and tamsulosin. The current protocols have demonstrated validation for linearity across concentration ranges of 3–20 μg/mL for mirabegron and 2–40 μg/mL for tamsulosin, utilizing dual wavelength, ratio difference, and derivative ratio techniques. The coefficients of determination exceeded 0.999. The validation of these methodologies was conducted in accordance with the guidelines set forth by the International council for Harmonization (ICH). Quality control laboratories may utilize existing techniques to identify the binary combination because of their high accuracy and cheap cost. The evaluation of the environmental sustainability of the established approaches was conducted using AGREE, GAPI, MOGAPI and whiteness revealing their notable eco-friendliness. The proposed method was deemed practical after the evaluation carried out with the Blue Applicability Grade Index (BAGI) assessment.