A simple, precise, and accurate high-performance thin-layer chromatography (HPTLC) method was developed and authenticated to perform simultaneous estimation of dapagliflozin propanediol monohydrate (DAPA), vildagliptin (VILDA), and metformin (MET) in active pharmaceutical ingredient (API) and tablet dosage form. It was found that there is not any reported stability-indicating HPTLC method for the simultaneous determination of DAPA, VILDA and MET; hence, this method was developed. Merck HPTLC silica gel 60 F254 plates were selected as the stationary phase. Acetonitrile, formic acid, and water (9:1:0.5, V/V) were the chromatographic solvents used. A densitometric study was conducted at the wavelength of 215 nm. For DAPA, VILDA, and MET, the concentrations used to conduct the study were 0.2‒0.6 μg/band, 2‒6 μg/band, and 10‒30 μg/band, respectively. The peaks of DAPA, VILDA, and MET have retardation factors (RF) of 0.70, 0.45, and 0.34, respectively. The regression coefficients (R2) of DAPA, VILDA, and MET were 0.9955, 0.9958, and 0.9972, respectively. The limit of detection values of DAPA, VILDA, and MET were 0.0018 µg/band, 0.0094 µg/band, and 0.1434 µg/band. The limit of quantification of DAPA, VILDA, and MET were 0.0056 µg/band, 0.0285 µg/band, and 0.4346 µg/band, respectively. With respect to International Council for Harmonisation (ICH) prerequisites, the accuracy, precision, and robustness outcomes were within suitable limits. The outcomes of stability data revealed that the degradation by acid, base, hydrogen peroxide, and water produced distinct peaks of DAPA, VILDA, and MET, along with a few other peaks, having different RF values. The forced degradation study for DAPA, VILDA, and MET was performed. DAPA was found to be stable in acidic, oxidative, and neutral conditions. Under acidic, basic, and oxidative conditions, VILDA was observed to be stable. The proposed technique passes all the ICH criteria; hence, it is an accurate, easy, suitable, and stable method for the analysis of DAPA, VILDA, and MET in combined dosage form.