Intracellular pH is a key indicator of cellular stability and plays a critical role in understanding biological processes and diagnosing various diseases. In this study, yellow-emitting carbon dots (C-dots) were synthesized via hydrothermal treatment of o-phenylenediamine and p-aminobenzoic acid. These C-dots exhibited pH-sensitive fluorescence, with intensity increasing as the pH ranged from 2.0 to 10.0, displaying a pK