Kayamkulam has a rich historical background connected to the old Odanad (Onattukara) kingdom of Kerala. In medieval times, Kayamkulam was an important princely state ruled by the Kayamkulam Rajas and was known for military strength, trade, and backwater transport.

During the 18th century, the powerful Travancore ruler Marthanda Varma conquered Kayamkulam and merged it into the Travancore kingdom after several battles. This marked the decline of the independent Kayamkulam kingdom.

The region later developed as a major trade and transport center because of its location near the Kayamkulam Kayal (backwaters) and important road and rail routes. Historical landmarks such as Krishnapuram Palace still preserve memories of the royal period.

Kayamkulam Municipality was formed to manage the growing urban area and civic administration of the town. Over the years, it expanded its role in public services such as sanitation, road development, water supply, and town planning. Today, it is one of the important municipalities in Alappuzha district and serves as a commercial hub of central Kerala.