The Kamala River (Hindi and Nepali: कमला नदी kamalā nadī) flows through Nepal and the Indian state of Bihar.
The Kamala originates from Churia Range near Maithan which is near Sindhuliagarhi in Sindhuli District of Nepal at an elevation of 1,200 metres (3,900 ft). It flows in a southerly direction crossing Kamala Khoj area and after passing through a gorge above Chauphat it flows into the terai area of Nepal at Chisapani. The Kamala forms the border between Siraha and Dhanusa districts in the terai. During the monsoon the river swells up and thus causes devastating river bank erosion. Tao River and Baijnath Khola River merges with Kamala at Maini
It enters Indian territory in Madhubani district in Bihar, 3.5 kilometres (2.2 mi) upstream of Jainagar. A barrage known as Kamala barrage has been constructed by the State Government near Jainagar. It joins the river Kareh (Bagmati) at Badlaghat in Khagaria district and the combined stream flows into the Koshi nearby. While one of its branches leads to the Bagmati another leads to the Kosi.