He was a longtime loyalist of former president Megawati Sukarnoputri and a senior member of her Indonesian Democratic Party of Struggle (PDI-P).

[1] Tjahjo Kumolo was Secretary General of PDI-P between 2010 and 2015, and was a member of the People's Representative Council (DPR) between 1999 and 2014 during which time he was the speaker of his party's faction until his replacement by later fellow minister Puan Maharani.

[3] During this period, he was elected leader of KNPI's (National Committee of Indonesian Youth) Central Java chapter.

[7] Prior to his tenure for the KNPI, Tjahjo Kumolo worked as a reporter for a daily paper in Central Java.

[11][12] Following Joko Widodo's election victory over Prabowo Subianto in 2014, Tjahjo Kumolo was selected as Minister of Home Affairs in the Working Cabinet and was officially sworn in on 27 October 2014.

[16][17] During his tenure, the ministry began evaluations on a variety of government bodies, assessing potential dissolutions or mergers to save costs and simplify bureaucracy.

[21] While his father was a Nahdlatul Ulama official in later life and his mother was a Muhammadiyah activist from Solo and so himself,[21] his extended family from both sides belonged to Gereja Kristen Jawi Wetan, a Protestant church.