He was born on June 17, 1848, in the Mangyongdae settlement of Joseon (now part of Pyongyang) as the eldest child of Kim Song-ryeong (김송령, 金成瑛; 1810–1899) and Na Hyeon-jik (나현직, 羅賢植; 1811–1897).

Contemporary writings and North Korean sources contradict each other regarding Kim Ŭngu's role in the General Sherman incident, when an armed American merchant ship sailed up the Taedong River with the intention of forcing the isolationist Joseon (modern day Korea) to open up to trade with the United States.

According to North Korea, the incident occurred as follows: The General Sherman arrived in Joseon in August 1866 (according to the lunar calendar it was still July).

The crew of the ship, which had originally arrived for trading purposes, decided to take an unexpected step and sailed on towards the interior of Pyongyang.

In North Korea, led by his successors, he is remembered to this day as the leader of the attack on the General Sherman and a national hero.