He was elected as a member of the Bihar Legislative Assembly in 2015 from Gopalganj.
In the 2005 and the 2010 Bihar Assembly elections, Subash Singh of the Bharatiya Janta Party won the seat by defeating Reyajul Haque from Rashtriya Janata Dal.
[2][3] In 2015, Subash Singh again won the seat by defeating Reyajul Haque from Rashtriya Janata Dal, with a margin of 5074 votes.
[4][5] Subhash Singh died at the All India Institute of Medical Sciences (AIIMS) in New Delhi on 16 August 2022.
He was ill for a long time, and after a kidney transplant, he was again admitted to the AIIMS.