Valmiki Nagar constituency is in the West Champaran district of Bihar, it is one of the 243 state legislative assembly constituencies of the state. It is also one of the 40 Lok Sabha constituencies from Bihar. 

The incumbent MLA from this constituency is Dhirendra Pratap Singh, alias Rinku Singh, from Janata Dal United (JDU). He won this seat in 2020, securing 74,906 votes, beating Rajesh Singh of the Indian National Congress (INC) by a margin of 21,585 votes. 

The Valmiki Nagar constituency has 3,45,890 registered voters, according to the 2024 data of the Election Commission of India. The number of registered male electors is 1,83,951 and female electors is 1,61,918. There are also 21 third gender electors registered in the constituency. The registered elector count has gone up from the 2020 elections which at the time was 3,31,874. In 2020, there were 1,78,445 male electors, 1,53,395 female electors and 34 electors were of the third gender. In 2015 the total elector count of the constituency was 2,95,342 with 1,61,252 male voters, 1,34,055 female voters and 35 voters from the third gender. 

The voter turnout from past elections was just a little over the halfway mark of the total registered electors in the constituency. In the 2020 elections, 1,95,791 out of the 3,31,874 registered voters cast their votes. The voter turnout stood at 59% that year.  In the 2015 elections 1,84,960 out of the 2,95,342 registered voters took part in polling, keeping the turnout at 62.63%. 

Polling for this constituency in the upcoming elections is set to take place during the second phase on November 11, 2025.

This constituency covers an approximate land area of 1290.47 square kilometers and the geographic coordinates of Valmiki Nagar are 26° 59 '51.0"N 84° 06' 13.3"E. A total of three Assembly constituencies in the state of Bihar share borders with Valmiki Nagar constituency, which are: Ramnagar, Bagaha and Lauriya. This constituency shares a border with the state of Uttar Pradesh and an international border with Nepal.