The structural, magnetic, dielectric and optical properties of Aurivillius Bi6Fe2Ti3O18-based ceramics were investigated in detail. The replacement of Co for Fe/Ti ions obviously varies the grain morphology. Compared with Bi6Fe2Ti3O18 (BFTO) with antiferromagnetic ordering, a spin glass state can be observed in Bi5.25La0.75Fe2Ti3O18 ceramic, while other samples exhibit the ferromagnetic behavior. The specimen Bi6Fe2Ti2(NbCo)(0.5)O-18 (BFTNCO) represents the largest remanent magnetization M-r of 0.93emu/g among all the samples, which can be attributed to the combination of a short lattice parameter c and a large lattice distortion as well as more magnetic ions in a unit cell. The room-temperature dc conductivity of BFTNCO is one order magnitude lower than that of BFTO. In addition, the band gaps of Co-doped samples are about 0.2eV smaller than these of Co-free samples. This work provides a promising path forward to tailor the multiferroic and optical properties in five-layered Aurivillius compounds.