The North Korean leader cried during his speech at the military parade on Saturday. The event marked the 75th anniversary of the ruling Worker’s Party.
Mr Kim apologised for not maintaining a better economy while addressing thousands of troops and citizens in Pyongyang.
He said he was “ashamed” of not being able to repay his people with economic prosperity in North Korea.
US President Donald Trump has imposed sanctions on the country.
He also convinced North Korea’s closest ally, China, to take part in a long-term strategy to force Pyongyang into denuclearisation talks.
But negotiations around total nuclear disarmament halted in 2019.
US officials, however, have said North Korea’s economic problems may lead Mr Kim to back down to Mr Trump’s demands, according to Newsweek.
On Saturday, Mr Kim took responsibility for North Korea’s failing economy.
Experts have said that heavy US and Chinese sanctions on North Korea together with Mr Kim’s focus on nuclear weaponry have hit the country’s economy.
Speaking at the military parade on Saturday, Mr Kim said: “Our people have placed trust, as high as the sky and as deep as the sea, in me, but I have failed to always live up to it satisfactorily.
“I am really sorry for that.
“Although I am entrusted with the important responsibility to lead this country upholding the cause of the great Comrades Kim Il-sung and Kim Jong-il thanks to the trust of all the people, my efforts and sincerity have not been sufficient enough to rid our people of the difficulties in their lives.”
A US official told the Guardian that it was “disappointing” that North Korea was continuing to prioritise nuclear and ballistic missile development.
They urged the country to “engage in sustained and substantive negotiations to achieve complete denuclearisation”.
At the military parade on Saturday, North Korea unveiled a new intercontinental ballistic missile.
North Korea’s trade with China has fallen dramatically due to border closures during the coronavirus pandemic.
Years of sanctions and natural disasters have also added to the struggling economy over the years.
Mr Kim warned on Saturday that he would “fully mobilise” his nuclear force if threatened.
Former White House national security adviser, John Bolton, has previously warned that Pyongyang “will never give up nuclear weapons voluntarily”.