This article reports on a comprehensive experimental study of O-16(+) and Zr-90(+) L ion co-implanted SrTiO3 (STO) single crystals. In this study, STO was used as a model material to simulate a waste form for disposal of radioactive Sr-90 that decays to Y-90 and subsequently to Zr-90 by emission beta(-) particles. Sequential O-16(+) and Zr-90(+) ion implantation at 550 K was performed and Zr and O atomic concentrations of up to 1.5 atom % each in STO were achieved. A number of analytical methods were employed to characterize the implanted STO, including secondary-ion mass spectroscopy, multiaxial ion-channeling analysis, and high-resolution X-ray diffraction. The results show that a high defect concentration was generated and accumulated in STO during the ion implantation, but the crystal structure was not rendered fully amorphous. Thermal annealing at 1273 K leads to a significant defect recovery at the surface with little recovery occurring at the damage peak, where a modest recovery occurs upon further annealing at 1423 K. Some of the implanted Zr species are well aligned with the STO < 001 > axis, but nearly all are barely located at the substitutional sites due to structural distortion. A minor phase with a tetragonal structure is observed in the Zr distributed region, which has the < 001 > axis parallel to that of the STO host. The tetragonal phase survived annealing at 1423 K with only a small decrease in the c parameter. A general assessment of the model waste form is also provided in this report.