The Korean Central Broadcasting Station said that Kim visited a testing site at a national defence institute and inspected the test of the unspecified new tactical weapon, reports Yonhap News Agency.
"The state-of-the-art weapon that has been long developed under the leadership of our party's dynamic leadership has a meaning of completely safeguarding our territory and significantly improving the combat power of our people's army.
"The testing of the high-tech tactical weapon has been carried out successfully, meeting all superior and powerful designing indicators," it said.
The Station reported that Kim praised scientists, saying they have made yet another achievement, calling the successful testing a great innovation in enhancing its national defence capacity.
He added that the development of the weapon was spearheaded by his late father and former leader Kim Jong-il.
Kim Jong-un was accompanied by Choe Ryong-hae, vice chairman of the ruling Workers' Party; Ri Pyong-chol, a senior official of the Munitions Industry Department; and Vice Department Director Jo Yong-won of the party's Central Committee.
The state media, however, did not specify the date of the test.
This marked the first field inspection by the North Korean leader of a weapons test since November 2017, when he viewed the testing of the Hwasong-15 intercontinental ballistic missile.
The inspection came as denuclearization talks between the North and US have stalled since their June 12 summit.