The Thejaswini River originates from the western slopes of the Greater Talacauvery National Park in the Brahmagiri hill ranges of the Western Ghats in Karnataka. Initially the river flows through several eastern hilly towns of the Kasargod district namely, Kozhichal, Odakolly, Palavayal, Pulingome, Theyyeni, Nallompuzha, Cherupuzha, Kadumeni, Kamballur, Vayakkara, Peralam, Bedhur, Perumbatta and Cheemeni. The river then enters the Malabar plains where it passes the towns of Karinthalam, Choyamkode, Kayyoor, Kilayikode and Nileshwaram. At reaching Nileshwaram, its tributary Kariangode River merges with it. Thejaswini then flows through Kariyil, Thuruthy and Thaikkadappuram. At Thuruthy, it bends south emptying into the Kavvayi estuary.^{[citation needed]}

Edathod river and Mayanganam river are the two tributaries of Neeleshwaram river.^{[citation needed]}