The bypoll for the Rajya Sabha seat arose following the death of Mohan Singh, a noted socialist.
Singh, accompanied by Chief Minister Akhilesh Yadav and Parliamentary Affairs Minister Azam Khan, filed her nomination at the Vidhan Sabha secretariat here.
Tomorrow is the last date for filing papers. Scrutiny will be held on Wednesday and the last date for withdrawal is December 12.
Voting, if required, will be held on December 20.