Kalyanpur (Vidhan Sabha constituency) (Hindi: कल्यानपुर विधान सभा निर्वाचन क्षेत्र) is an assembly constituency in Purvi Champaran district in the Indian state of Bihar.
As per orders of Delimitation of Parliamentary and Assembly constituencies Order, 2008, 16. Kalyanpur (Vidhan Sabha constituency) is composed of the following: Kotwa community development block; Parsauni Wazid, Bakhri, Kalyanpur, Barharwa Mahanand, Siswa Shobh, Brindaban, Pakari Dixit, Siswa Kharar, Patna, Gariba, Shambhu Chak, Sitalpur, Koela Belwa, Bhuwan Chhapra, Banshghat, North Gawandra, South Gawandra and Mani Chhapra gram panchayats of Kalyanpur CD Block.
Kalyanpur (Vidhan Sabha constituency) is part of 3. Purvi Champaran (Lok Sabha constituency).
Election results 
In the November 210 state assembly elections, Razia Khatoon of JD(U) won the newly created 16 Kalyanpur assembly seat defeating her nearest rival Manoj Kumar Yadav of RJD.