Prior to entering politics, he was an activist at Korea University, where he served as the president of its student union.

[4][5][1] He was briefly detained for occupying the-then ruling Democratic Justice Party (DJP) headquarter.

[3] He was appointed the Secretary to the President for Political Affairs of the Blue House following the victory of the ex-UDP Chairman in 1992 presidential election.

[18] On 30 May 2017, Kim was nominated the Minister of Oceans and Fisheries by the newly elected President Moon Jae-in.

[19] On 17 June, the next day of his appointment, Kim visited Mokpo New Port for inspect the MV Sewol in order to recover uncollected bodies and settle unsolved issues.

[25][26] On 26 November 2019, Kim showed his intention to run for the 2022 presidential election, citing an example of the former Oceans and Fisheries Minister Roh Moo-hyun who later became the President.

[30] In June 2020, he was appointed as the 33rd Secretary-General of the National Assembly responsible for its administration by the newly elected Speaker Park Byeong-seug.

[31] The resignation of the Mayor of Busan Oh Keo-don on 23 April 2020 following the allegations of sexual harassment has provoked the by-election in 2021.

[35] On 28 December, he officially resigned from the Secretary-General of the National Assembly; this was described by several media as "de facto confirmation to contest in the election.

"[36][37][38] On 12 January 2021, Kim officially launched his bid for Busan mayorship at Nameless Diary, a complex cultural space in Yeongdo.

[39] Then, he suggested "3 Dreams", they are:[39][40] Following are the manifestos he has promised:[39][41] On 6 March 2021, Kim won Democratic preselection by obtaining 67.74%, defeating the former Deputy Mayor Byeon Sung-wan (25.12%) and the former Speaker of the Busan Metropolitan Council Park In-young (7.14%).

[43][44][45][46][47][48][49][50][51][52][53][54][55] The exit poll released shortly after the election on 7 April showed that Kim could only secure 33.0%, compared to Park who was expected to obtain 64.0%.