He was the president of Tamil Nadu Congress party from 2019 to 2024.
[4][5] He was hospitalized on July 28, 2023, after he fell down and got injured during a walking session.
He graduated from Annamalai University, Chidambaram and is a native of Cuddalore district in North Tamil Nadu.
In November 2022, there was a rebellion against K. S. Alagiri by TNCC party leaders seeking replacement of Alagiri's term as the party president.
The leaders met Congress president Mallikarjun Kharge and complained about Alagiri's functioning methods and not countering the BJP in the state adequately.