Purple sweet potato (PSP) is recognized for its high content of anthocyanins, dietary fiber, and bioactive compounds, thereby holding potential to enhance the nutritional value, physicochemical characteristics, and shelf life of the product. This study aimed to evaluate the effects of varying concentrations of steamed PSP on the physicochemical and sensory qualities of yogurt made from commercial milk. A Completely Randomized Design (CRD) with five treatments, P0-P4 (0%, 2%, 4%, 6%, and 8% steamed PSP) and five replications was employed. The parameters observed included pH, total lactic acid, viscosity, antioxidant activity, color (L*, a*, b*), and Sensory evaluation. This method was selected to assess variation systematically and controllably in yogurt quality across different treatments. The results showed that the addition of steamed PSP significantly (p < 0.05) increased antioxidant activity, viscosity, purple color intensity (L*, a*, b*), total lactic acid, and panelists’ preference for aroma, taste, color, and texture as demonstrated by the ANOVA results. Among treatments, P2 (4%) and P4 (8%) were most preferred by the panelists, likely due to their optimal balance of natural sweetness, appealing purple colour, and thicker texture, without excessively altering the characteristic properties of yoghurt.