Prior to serving as mayor, he was a democratic movement student activist and a member of the Korean National Assembly for three terms.

Song, Young-gil was born in Goheung, South Jeolla Province, the fourth son of a poor civil servant.

Based on his experience as a lawyer, Song applied to work for the Legislation & Judiciary Committee to take care of bills that are closely related to the people's livelihood and human rights.

Song also assumed the role of Chairman of the Democratic Party's Commission on the Yong-san Tragedy to negotiate with the government and Seoul City over much delayed compensation and funeral issues.

[3] In October 2008, they announced a resolution which called for the release of Aung San Suu Kyi from house arrest and expressed support for the Myanmare people who continued to struggle against the junta.

In this context, Song went to Pyeongyang with young businessmen in 2003 and discussed the possibility of expanding economic cooperation and cultural exchanges between the two Koreas.

Song has also visited Gaeseong Industrial Complex several times which has been playing a critical role in ensuring the self-reliance of North Korea and contributing to peace on the Korean Peninsula and in the world.

He held meetings with businessmen and government officials to encourage more companies to move to the North which might in turn induce the communist nation to introduce reform and openness.

He also called on the government to enter dialogue with the North and to closely cooperate with neighboring countries to form 6-party talks which play such a vital role in the joint security of Northeast Asia.

Despite opposition from the government, he has insisted that there should be peace on the 5 islands near the Northern Limit Line in the West Sea for the economic development of Incheon.

In 2008, most small exporting firms bought currency option products called KIKO (Knock-in Knock-out) to avoid the risk of foreign exchange rate fluctuations.

By forming a special committee, he held dozens of meetings with small enterprises and led hearings to narrow differences and find solutions.

In 2008, the results of the US presidential election and the Democratic Party's regaining control after 8 years demanded new cooperation and close exchanges between Korea and the US.

He believes that the U.S. should lead the easing of sanctions on North Korea, recognition of the Kim Jong-un regime, and declaration of the 'Declaration of the end' (종전선언 or 종전협정).

With the announcement of his running, Song talked about his plans for nurturing small enterprises, balancing development between the old and new town, expanding welfare provision, enhancing educational competitiveness, and providing free eco-friendly meals to make Incheon the economic capital of Korea.

On 1 March 2016, Song declared that he is running for the National Assembly as a Democrat in Incheon's Gyeyang (B) constituency, which he represented in previous years.

However, he decided to run in Gyeyang (B) after assemblyman Choi, Won Sik leaves the Democratic Party despite Song's persuasion to stay.

He returned to the National Assembly after 6 years since he ran for the 5th General election in 2010 On 24 July 2016, He declared his running for the party leadership.

In following August, Song became the chairman of the Presidential Committee on Northern Economic Cooperation., which holds the equivalent grade of a deputy prime minister.

On December 19, 2023, the prosecutor's office arrested Song Young-gil on charges of distributing bribes to win the 2021 Democratic Party of Korea leadership by-election.

[citation needed] He was acquitted of the charges in the leadership election, but was convicted and sentenced on January 8, 2025, to two years imprisonment for receiving illegal political funding from seven businesspeople.