The Korean Central News Agency reported Kim "elevated our country into a nuclear state" and "made immortal contributions to global peace and stability," South Korea's Yonhap News Agency reported.
The designation gives Kim, who died in December, the same rank as his late father, North Korea's founder, Kim Il Sung, The Korea Times said.
A bronze statue of Kim Jong Il riding on a horse was unveiled in Pyongyang ahead of celebrations for his birthday Thursday.
Birthday celebrations also will include a fireworks display at what North Korea says is Kim's birthplace at the foot of Mount Baekdu, near the China border.
Kim's official biography says he was born there in 1942 but experts say he was born a year earlier in a village in the Soviet Union, where his father led a brigade of Chinese and Korean exiles, the Times said.
North Korea apparently has ordered people studying or working abroad to return home by Thursday to mark the birthday, The Chosun Ilbo reported.