Chalakudi River flows through the town of Chalakudy in the Thrissur district of Kerala, which is in south India. With a length of 145.5 kilometers, it is the fifth longest river in India. The total drainage area of the river is 1704 square kilometers, out of which 1404 square kilometers lie in Kerela and 300 square kilometer in Tamil Nadu.

The river has its origin in the Anamalai region of Tamil Nadu, which several tributaries from Parambikulam, Kuriyarkutti, Sholayar, Karapara and Anakayam merge together. The river passes through Thrissur and Palakkad districts before merging with the Periyar River at Puthanvelikkara village in Ernakulam District. The main tributaries of the river are Parambikulam, Kuriyarkutti, Sholayar, Karapara and Anakayam. The Parambikulam Dam has been constructed on the Parambikulam River, one of its four tributaries.

The Athirappilly Waterfalls and Vazhachal Waterfalls are part of the Chalakudi river stream. The Sholayar Dam, which is 65 kilometers in the east of Chalakudi town and the Peringalkuttu Hydro-Electric project are constructed across the Chalakudi River.