Electric field modulations of the perpendicular magnetic anisotropy (PMA) and magnetization dynamics of MgO/Co/Pt trilayers were measured by time-resolved magneto-optical Kerr effect (TRMOKE). The anisotropy field estimated from the anomalous Hall effect applying a field along in-plane was confirmed to be modified by the electric field, which results in the PMA variation with an electric field of −32 fJ/(<inline-formula> <tex-math notation="LaTeX">$\text{V}\cdot \text{m}$ </tex-math></inline-formula>). The PMA variation was also confirmed from TRMOKE measurements, which was estimated to be −47 fJ/(<inline-formula> <tex-math notation="LaTeX">$\text{V}\cdot \text{m}$ </tex-math></inline-formula>). From TRMOKE measurements, we also observed the reduction of the inverse of relaxation time 1/<inline-formula> <tex-math notation="LaTeX">$\tau $ </tex-math></inline-formula> of the magnetization precession with increasing the electric field. The 1/<inline-formula> <tex-math notation="LaTeX">$\tau $ </tex-math></inline-formula> was analyzed by assuming the contributions of effective Gilbert damping <inline-formula> <tex-math notation="LaTeX">$\alpha _{\text {eff}}$ </tex-math></inline-formula>, anisotropy distribution, anisotropy angle distribution, and two magnon scattering, and we found <inline-formula> <tex-math notation="LaTeX">$\alpha _{\text {eff}}$ </tex-math></inline-formula> decreased with increasing the electric field whose modulation was −0.0046 nm/V, corresponding to −13% per 1 V/nm. These results are similar to the electric field effect in (001)-orientated MgO/CoFeB/Ta trilayers, however, our finding indicates similar PMA and <inline-formula> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula> modulations are found in MgO/Co/Pt trilayers having MgO(111)/fcc-Co interface.