As a Janata Party candidate, he was elected to the Haryana Legislative Assembly from the Bhattu Kalan constituency in 1982 and has been re-elected on five occasions.
Sampat Singh was born in the village of Bhattu Kalan, Fatehabad District, Haryana, on 20 April 1949.
Singh stood unsuccessfully in the Bhattu Kalan constituency by-election of 1980, claiming afterwards that he lost "because of widespread use of unfair means".
[4] He described the INLD as being in "complete disarray", no longer aligned with the principles of Devi Lal and subject to the nepotism of its then leader, Om Prakash Chautala.
[7] As an INLD politician, Singh contested the 2009 Indian general election from Hisar Lok Sabha constituency on a National Democratic Alliance ticket.