Changanacherry and the surrounding areas were part of a kingdom called vempolinadu during 12th century C.E. Upon the disintegration of the kingdom, Changanacherry became part of the Thekkumkoor monarchy until 1753 C.E. Thekkumkoor kingdom initially covered a large area including Thiruvalla and beyond. Village areas under the kingdom were given administrative heads called ‘Karanavar’ by the kings. Brahmins were considered exclusively for this position.

The history of Changanacherry is incomplete without the mention of the conquest of Marthanda Varma and Ramayyan Dalava. Anizham Thirunaal Marthanda Varma (1729-1758), the king of Venad, took Thekkumkoor kingdom in 1953 with an aim of establishing Thiruvithamkoor (Travancore). A brilliant administrator (dalava/diwan) called Rama Iyer (also called Ramayyan) was the mastermind behind the creation of Travancore. He was undoubtedly the best military general Kerala has ever seen. Nothing seemed to stand in his way as Ramayyan took Thiruvalla and next he set his eyes upon Thekkumkoor kingdom. But unlike any of the kingdoms which he had conquered, Thekkumkoor had a much larger and stronger army.

The king of Thekkumkoor got a wind of Ramayyan’s plans to take down Thekkumkoor kingdom from Changazhimattom Potti. He advised the king to destroy a bridge, located a kilometer north of Vazhapally area that connected Changanacherry with Thuruthy area. He thought it was a masterstroke enough to stop Ramayyan’s army.

Little did he know that, Ramayyan had some other plans in his mind. By then, Ramayyan had won over the chief of Thekkumkoor’s army, Vaazhappaadathu Panicker. Panicker could not refuse the gifts and other bribe that Ramayyan offered him. Panicker provided the complete information about Potti’s plans to Ramayyan. It led to Ramayyan’s army reaching Kottayam without any resistance. Thekkumkoor king fled to Kozhikode and took refuge in local king, Samoothiri’s palace. King of Venad showered gifts on Panicker.

Marthanda Varma promised Thekkumkoor king that he would be treated honorably lest he wishes to come back. Thekkumkoor king eventually settled in Nattassery, north of Kottayam.

The last Thekkumkoor raja can be named as the most efficient and revered king Kerala has ever seen. No other king could match his secular outlook, farsightedness, intense wish to serve his subjects. He asked Changazhimattom Potti to donate land for churches and mosques. It was he who started the Muslim festival of ‘Chandanakudam’. He provided full protection and encouragement to the business community irrespective of their caste and religion. With the help of Christian and Muslim business community, he developed Changanacherry as a major commercial centre of his kingdom. The credit for the further development of Changanacherry goes to the Travancore kings.

The Kerala Government through an ordinance in 1991 officially changed the town’s name to Changanassery.