Bihariganj (Vidhan Sabha constituency) (Hindi: बिहारिगंज विधान सभा निर्वाचन क्षेत्र) is an assembly constituency in Madhepura district in the Indian state of Bihar.
As per Delimitation of Parliamentary and Assembly constituencies Order, 2008, No. 71 Bihariganj (Vidhan Sabha constituency) is composed of the following: Bihariganj and Gwalpara community development blocks; Biriranpal, Madhuban, Rampur Khora, Kishunganj, Lakshmipur, Barahi Anadpura and Pipra Karoti gram panchayats of Uda Kishunganj CD Block; Gram Panchayats Haripur Kala, Digghi, Singiyon, Raghunathpur, Kolhaypatti Dumriya, Rajni, Gangapur, Dinapatti Sakhuwa, Pokhram Parmanadpur, Jorgama, and Rampur gram panchayats and Murliganj notified area of Murliganj CD Block.
Biharganj (Vidhan Sabha constituency) is part of No. 13 Madhepura (Lok Sabha constituency).
In the 2010 state assembly elections, Renu Kumari of JD(U) won the newly created Bihariganj assembly seat defeating her nearest rival Prabhash Kumar of RJD.