An optical sensing apparatus includes a sensing unit, an analog/digital conversion unit, a switching unit, a first processing unit, and a second processing unit. The sensing unit provides a light sensing signal. The analog/digital conversion unit is coupled to sensing unit and converts light sensing signal into a digital light sensing signal. The switching unit is coupled to analog/digital conversion unit and selectively switched to a first mode or a second mode according to a mode control signal. The first processing unit and second processing unit are coupled to analog/digital conversion unit and switching unit. When switching unit is switched to first mode according to mode control signal, first processing unit generates a photoplethysmography (PPG) signal according to digital light sensing signal when switching unit is switched to second mode according to mode control signal, second processing unit generates a proximity sensing signal according to digital light sensing signal.
