We propose that the possible 750 GeVdiphoton excess can be explained in the color-octet neutrino mass model extended with a scalar singlet Phi. The model generally contains N-s species of color-octet, electroweak doublet scalars S and N-f species of color-octet, electroweak triplet chi or singlet rho fermions. While both scalars and fermions contribute to the production of Phi through gluon fusion, only the charged members induce the diphoton decay of Phi. The diphoton rate can be significantly enhanced due to interference between the scalar and fermion loops. We show that the diphoton cross section can be from 3 to 10 fb for O(TeV) color-octet particles while evading all current LHC limits.