Kim ordered the lifting of maximum anti-epidemic measures imposed in May though added that North Korea must maintain a "steel-strong anti-epidemic barrier and intensifying the anti-epidemic work until the end of the global health crisis", North Korea's KCNA news agency reported on Thursday.
North Korea has never confirmed how many people caught COVID-19, apparently because it lacks the means to conduct widespread testing.
Instead, it has reported daily numbers of patients with fever, a tally that rose to some 4.77 million. But it has registered no new such cases since July 29.
Kim made his declaration in a speech on Wednesday at a meeting on COVID-19 policy with thousands of unmasked officials sitting indoors, according to footage from state broadcasters.
Kim's sister, Kim Yo-jong, also addressed the gathering and said the young leader himself had suffered from fever symptoms, according to KCNA, indicating for the first time that he was likely infected with the virus.
"Even though he was seriously ill with a high fever, he could not lie down for a moment thinking about the people he had to take care of until the end in the face of the anti-epidemic war," she said in remarks broadcast on North Korean state television.
Some of the officials at the meeting were shown wiping away tears as she spoke about her brother's illness.
She did not elaborate on Kim's health but blamed propaganda leaflets from South Korea found near the border for causing the coronavirus outbreak.
North Korean defectors and activists in the South have for decades floated balloons carrying anti-Pyongyang leaflets into the North, at times along with food, medicine, money and other items.
Kim Yo-jong criticised South Korea's new government of President Yoon Suk-yeol for seeking to lift a 2020 ban on the leaflet campaigns, calling the South an "invariable principal enemy".
"We can no longer overlook the uninterrupted influx of rubbish from South Korea," she said, threatening to "wipe out" South Korea's authorities.
"Our countermeasure must be a deadly retaliatory one."
South Korea's Unification Ministry, which handles cross-border relations, expressed regret about North Korea's repeated "groundless claims" regarding the origin of its COVID-19 outbreak and its "rude and threatening remarks".
Defence Minister Lee Jong-sup told reporters North Korea's accusation was "more likely making an excuse for provocations".
Analysts said although the authoritarian North has used the pandemic to tighten social controls, its victory declaration could be a prelude to restoring trade hampered by border lockdowns.
"The meeting seems primarily aimed at fostering unity among the people but could also be to send a message to China that they're COVID-free and ready to restart trade," said Yang Moo-jin, a professor at the University of North Korean Studies in Seoul.
Analysts have also said the easing of restrictions may clear the way for the North to test a nuclear weapon for the first time since 2017.
North Korea's official COVID-19 death rate of 0.0016 per cent, or 74 out of some 4.77 million, is an "unprecedented miracle", its anti-virus chief Ri Chung Gil told the meeting.
The World Health Organisation has cast doubts on North Korea's assertions.
