Wilms' tumor is the most common pediatric solid renal tumor. Cross-fused renal ectopia is a rare congenital anomaly in which the left and right kidneys become fused and fail to ascend from the pelvis and abdomen. We report a case of a 5-year-old girl that underwent open partial nephrectomy on a cross-fused ectopic kidney, “pancake kidney,” after incidental discovery of a solid renal mass found to be a Wilms' tumor. Thorough review of the literature shows that this combination of Wilms' tumor in the setting of cross-fused renal ectopia has only been reported twice previously.