He was assigned Dairy And Milk State Minister in Akhilesh Yadav's cabinet in Uttar Pradesh.
Sunil Singh Yadav was part of a delegation as national president of Samajwadi Chhatra Sabha which visited China on 20 September 2011.
Sunil was the architect of the first agitation by the SP against the current Bahujan Samaj Party government, on 8 January 2008, when it sought restoration of the students' union and opposed fee hike.
While Leader of the Opposition Shivpal Singh Yadav was slapped by a policeman, an SP worker lost his life in police firing.
[12] On 27 April 2014 UP Chief Minister Akhilesh Yadav sent his point man Sunil Singh Sajan to lead a team of 50 party volunteers with the relief material from the state for the needy people in quake hit Kathmandu.