Gov. Jerry Brown's administration announced Friday that he had appointed Martin Hoshino, who is the department's undersecretary of administration and offender services.
Hoshino will become acting secretary at midnight Sunday, when current Secretary Matthew Cate officially steps down.
Cate announced last month that he would leave to become executive director of the California State Association of Counties.
He oversaw a historic shift in the state's criminal justice system that is sending thousands of lower-level criminals to county jails instead of state prisons.
Brown appointed Hoshino undersecretary in May 2011. He previously has served as executive officer for the Board of Parole Hearings and as chief assistant inspector general.