Unilateral facet dislocation at the subaxial cervical spine (C3–7) in children younger than 8 years of age is rare. The authors describe a surgical approach for irreducible subaxial cervical unilateral facet dislocation (SCUFD) at C3–4 in a 5-year-old boy and present a literature review. A dorsal unilateral approach was applied, and a biodegradable plate was used for postreduction fixation without fusion after failed conservative treatment. There was complete resolution of symptoms and restored cervical stability. Two years after surgery, the patient had recovered range of motion in C3–4. In selected cases of cervical spine injury in young children, a biodegradable plate can maintain reduction until healing occurs, obviate the need to remove an implant, and recover the motion of the injured segment.