Three-dimensional-ordered Yb/Er co-doped Bi2Ti2O7 inverse opal, powder, and disordered reference samples are prepared and their upconversion (UC) emission properties and mechanisms are investigated. Significant suppression of UC emission is detected when the photonic band-gaps overlap with Er3+ UC green emission bands. Interestingly, green and red UC emissions follow a two-photon process in the powder sample but a three-photon one in the inverse opal.