This study investigates the effects of yeast application with fermentation durations on physicochemical properties such as total soluble solids (TSS), titratable acidity (TA), and potential hydrogen (pH), and microbial colony-forming units (CFU/g) of bacteria in Arabica coffee fermentation. Yeast and fermentation duration produced a substantial combined effect on the properties of coffee. The sugar metabolism activities in yeast-fermented coffee reduced TSS, although TA levels increased and pH measurement decreased because of acid accumulation. The colony-forming unit (CFU/g) of bacteria varied significantly in all treatments, with yeast treatments increasing CFU/g after fermentation and gradual reduction after drying, while longer fermentation durations influenced the decrease of CFU/g but led to increased CFU/g after drying, particularly at 72 hours. The statistical analysis revealed highly significant results across all treatment combinations. This is how yeast fermentation under controlled conditions shapes sugar metabolism during the fermentation process, as well as affects acid production and microbial populations, which results in enhanced coffee quality properties.