Kim Yong-nam, North Korea's octogenarian ceremonial head of state, lauded Kim Jong-un who is in his late 20s as "the supreme leader of our party and army and people," claiming the successor fully personified the ideas, leadership, personality, virtues, grit and courage of his late father.
"We will turn sorrow into thousand-fold strength and courage, and tide over the present difficulties," Kim Yong-nam told tens of thousands of troops in Kim Il-sung Square in Pyongyang.
He also vowed to build "a thriving socialist nation," by "holding Kim Jong-un in high esteem as another General and supreme leader."
North Korea, one of the poorest countries in the world, has vowed to build a prosperous nation by next year, the centennial of the birth of late Kim's father, the country's late founder Kim Il-sung.
The memorial service is an official proclamation that Kim Jong-un will lead the communist country through the political and diplomatic challenges of the crucial transition period.
The new leader had been groomed to succeed his father as the country's next leader only since his father suffered a stroke in 2008. The junior Kim made his public debut last year when he was named a four-star general and vice chairman of the ruling Workers' Party.
Kim Jong-gak, a top military officer, told the packed audience in the square in cold weather that the country's 1.1 million soldiers "will safeguard comrade Kim Jong-un with their lives."
Winning support from the military, which served as a key backbone of the late Kim's totalitarian rule, is seen as key for the young leader in consolidating his power.
Kim Jong-un, wearing a black coat, did not make any public comment as he watched the somber memorial service for his father, who was reported to have died suddenly of heart failure on Dec. 17.
The young leader, flanked by key party and military officials, observed three minutes' silence along with the troops packed into the square, as soldiers fired volleys in memory of his father.
"Locomotives and ships also blew whistles and those units with sirens sounded them all at once," the North's official Korean Central News Agency reported.
The memorial service came a day after North Koreans paid an emotional tribute to the late Kim. His body lies in state at the Kumsusan Memorial Palace in Pyongyang, home to the embalmed body of his father and North Korea founder Kim Il-sung.