Singh had resigned from the People's Democratic Party (PDP) as well as the Member of Legislative Council post on October 24 this year.
He had announced his resignation on October 22, saying it was not possible for him to continue with the party which "disregarded the demands and aspirations of the Jammu region".
PDP chief and Chief Minister Mehbooba Mufti accepted Singh's resignation from the PDP last week.
A notification issued by the Secretary Legislative Council further reads that the seat occupied by Singh has fallen vacant with effect from October 24, 2017.
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He was a member of the State Legislative Council.
"I have sent my resignation to party president Mehbooba Mufti with a request to accept it immediately. I feel that it is neither morally nor ethically right for me to continue as a member of the PDP," Singh has told reporters then.
Singh, son of senior Congress leader Karan Singh, claimed, "I have publicly expressed my concerns for our state in general and Jammu in particular over the last several months but the party has rejected the issues.