An inclusion complex of NaYF4:Yb3+, Er3+ upconversion nanoparticles with a cyclodextrin in aqueous conditions exhibits luminescence quenching when excited at 980 nm. This non-radiative relaxation leads to an unprecedented photoacoustic signal enhancement. In vivo localization of alpha-cyclodextrin-covered NaYF4:Yb3+, Er3+ is demonstrated using photoacoustic tomography in live mice, showing its high capability for photoacoustic imaging.