Background: Spinal fusion is a common procedure that provides spinal stability by connecting vertebral segments using a bone graft. Because the spinal alignment is fixed permanently after spinal fusion, a mal-aligned fusion can produce iatrogenic spinal deformity and imbalance with significant disability. Current Concepts: Failure to restore adequate segmental lordosis in lumbar spinal fusion is a common cause of iatrogenic spine deformity. Local and regional spinal deformities can affect the global alignment; accordingly, spinal imbalance can occur when the compensation mechanisms fail. Diagnosis and surgical planning should be made on a thorough analysis of global and spinopelvic parameters on the standing whole-spine radiographs. Surgical treatment includes neural decompression, spinal fusion, and deformity correction. Spinal osteotomy provides a favorable surgical outcome, although the complication rate is high. Discussion and Conclusion: Iatrogenic spine deformity is increasing due to the increased occurrence of spinal fusion surgery. To prevent iatrogenic spine deformity, the index fusion surgery should be performed based on a comprehensive analysis of spinopelvic alignment and balance.