The magnetic and magneto-optic properties of epitaxial CeY2Fe5O12 (Ce∶YIG) and Y3Fe5O12 (yttrium iron garnet or YIG) thin films grown by pulsed laser deposition on gadolinium gallium garnet substrates are determined. An enhanced Faraday effect is known to result from Ce substitution into the yttrium iron garnet lattice, and here we characterize the magneto-optic Kerr effect, as well as the magnetic hysteresis and ferromagnetic resonance response that result from the Ce substitution. X-ray diffraction analysis reveals a high crystallographic quality for the Ce∶YIG films. Measurements of the magneto-optic Kerr effect for two different wavelengths demonstrate that the Ce∶YIG exhibits an up-to-tenfold increase in Kerr rotation compared to YIG. The Ce∶YIG has a slightly larger magnetic moment, as well as increased magnetic damping and higher magnetic anisotropy compared to YIG with a dependence on the crystalline orientation. By specific cerium substitution in YIG, our results show that the engineering of a large Kerr effect and tailored magnetic anisotropy becomes possible as required for magneto-optically active spintronic devices.