Using the SDSS and Pan-STARRS1 survey data, we found a likely companion of the recently discovered binary γ-ray radio-loud millisecond pulsar J0621+2514. Its visual brightness is about 22 mag. The broadband magnitudes and colours suggest that this is a white dwarf. Comparing the data with various white dwarfs evolutionary tracks, we found that it likely belongs to a class of He-core white dwarfs with a temperature of about 10 000 K and a mass of ≲ 0.5 M⊙. For a thin hydrogen envelope of the white dwarf, its cooling age is ≲ 0.5 Gyr which is smaller than the pulsar characteristic age of 1.8 Gyr. This may indicate that the pulsar age is overestimated. Otherwise, this may be explained by the presence of a thick hydrogen envelope or a low metallicity of the white dwarf progenitor.