The ceremony in central Pyongyang, marking the second death anniversary of Kim's father and former leader Kim Jong-Il, included a number of speeches that stressed unquestioning loyalty to the young supremo and included a stark warning to rival South Korea.
It followed the shock execution last week of Kim Jong- Un's uncle and one-time political mentor, Jang Song-Thaek.
The purge raised questions about factional infighting at the top of the North Korean hierarchy and prompted both Seoul and Washington to warn of possible provocative acts by the nuclear-armed regime.
"We should be warriors to safeguard the party centre with our lives ... With the conviction that we know no one but the great comrade Kim Jong-Un," North Korea's ceremonial head of state, Kim Yong-Nam, said in an opening address.
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He added that the country had made "great strides" in the two years since Kim took over the reins of power after his father's death.
"By holding the respected comrade Kim Jong-Un in high esteem... Our country will prosper as the country of eternal sun," Kim Yong-Nam said.
Today's mass meeting also heard a keynote address by top military leader Choe Ryong-Hae -- who some analysts believe had a hand in the ouster and execution of Jang Song-Thaek.
"Our revolutionary forces know... No one but comrade Kim Jong-Un," said Choe, a close Kim Jong-Un confidant who holds the military rank of vice marshal and is director of the Korean People's Army's General Political Department
"If the enemies drop a single drop of fire on our motherland, our soldiers will immediately storm out to wipe out all the invaders and achieve unification," he said.
At a meeting of top defence and national security officials yesterday, South Korean President Park Geun-Hye had warned that the recent leadership shake-up in the North could presage some aggressive behaviour from Pyongyang.