Valmiki Nagar (Vidhan Sabha constituency) (Hindi: वाल्मीकि नगर विधान सभा निर्वाचन क्षेत्र) is an assembly constituency in Paschim Champaran district in the Indian state of Bihar.
As per orders of Delimitation of Parliamentary and Assembly constituencies Order, 2008, No. 1 Valmiki Nagar (Vidhan Sabha constituency) is composed of the following: Piprasi, Madhubani, Thakrahan and Bhitaha community development blocks; and Valmiki Nagar, Laxmipur Rampurwa, Santpur Soharia, ChampapurGonauli, Naurangia Dardari, Mahuawa Katharawa, Harnatand, Balua Chhatraul, Dewaria Taruanwa, Bharachhi, Belahawa Madanpur, Bakuli Panchgwa, Binwalia Bodhser, Nayagaon Rampur, Mangalpur Ausani, Borawal Narawal, Semra Katkuiya, Yamunapur Tadwalia, Jimari Nautanawa and Dholbajwa Laxmipur gram panchayats of Sidhaw CD Block.
Valmiki Nagar (Vidhan Sabha constituency) is part of No. 1 Valmiki Nagar (Lok Sabha constituency).
Election results 
In the November 2010 state assembly elections Rajesh Singh of JD(U) won the newly created No. 1 Valmiki Nagar Vidhan Sabha seat defeating his nearest rival Mukesh Kumar Kushwaha of Rashtriya Janata Dal.