A dibenzo[hi,st]ovalene (DBOV) derivative bay-substituted with two piperazinylphenyl (PZP) groups (DBOV-PZP) was synthesized. Comprehensive investigations of its photophysical properties revealed acid-induced fluorescence enhancement through the protonation of PZP units, leading to the suppression of the photoinduced electron transfer. These results pave the way towards "turn-on" type nanographenes for biosensing and optical imaging.