According to Hindu factology, Irinjalakuda was created by sage Parasurama. According to Keralolpatthi, out of the 64 gramas (villages) established in Kerala( Out of these 32 Malayala Gramas & one Thulu grama viz.Manjeswaram are in the present Kerala and 31 Thulu Gramas in the Coastal Karnataka.), Irinjalakuda was the head of 10 of them. Irinjalakuda was one of the most prominent among these villages. Like the other villages this Grama also followed the Chathurvarnia system of society with some Kerala model variations which lay upon caste system based on the Manusmruthi.
The name Irinjalakuda has been derived from "Iru" and "Chaal", meaning two streams. According to another legend, the origin of the name Irinjalakuda came from Irinjalikoodal. Koodal simply means merge, merging of two rivers. Two streams that start, one from Kurmalipuzha and move through Konthipulam at North whereas the other from Kudapuzha, that belongs to Chalakudypuzha,and move through, in between Chalakudy and Potta,South of Aloor desom,Thazhekkad,in between Avittathur and Pullur,Velukara at South. Then these two streams merge in the West. So it shows that Irinjalakuda may have gradually developed, from Irinjalikoodal, that derived from Inangikoodal, means merge. At present there is no river in Irinjalakuda, only the myth of river.
In the last decade of the 18th Century the last Naduvazhi Nambiar of Mukundapuram Nadu or Murija Nadu was died and Sakthan Thampuran, the Ruler of Kochi formed Mukundapuram taluk by adding Mapranam Nadu and Nandilathu Nadu to Mukundapuram Nadu(Muriya Nadu).Sakthan Thampuran divided old Mukundapuram Nadu into Three Proverties viz.1) Thazhekkad (Aloor,Kallettumkara,Kombodinjamakkal& Muriyad)2) Aripalam (Poomangalam,Padiyoor & Vellangallur),3)Mukundapuram (Nadavarambu,Irinjalakuda,Kottanellur,Kaduppassery &Pullur ) and old Mapranam Nadu into a single Mapranam Proverty(Kattur,Karalam,Porathussery&Madayikkonam) for administrative and revenue purposes .Old Irinjalakuda Municipality was part of Mukundapuram Proverty up to AD1905.
Another legend suggests that the origin of the name Irinjalakuda were heard, "Irunnu Salayil Koodai", and "Virinja Alu Kuda". There is a huge Banyan tree still standing in the centre of the Irinjalakuda spreading the branches to the sky like an umbrella. Tippu Sulthans Army was based at Aloor-Thazhekkad area of Mukundapuram Nadu on 24th December 1789 to attack the Nedumkotta which is situated in the middle of Kochi Kingdom and was known as Travancore lines and attacked KonurKottavathil in January1790.Before the arrival of Tipu Sulthan to Mukundapuram Nadu in December1789 the hedquarters of Padruado Archbishops of Cranganore(Kodungallur)of Nazranis was at Pookkatt(Aripalam) of Mukkundapuram Nadu.(See Varthamanpusthakam of Paremakkal Thoma Kathanar,Gobernador and ArchaDeacon of late Eighteenth century). Sakthan Thampuran brought four Christian families for improving commerce and trade to the place known as ‘Chanthappura’. When they struck gold in this field, more of this community migrated from Kombara chantha and settled in the area and now it became one of the strongholds of this community. Besides Hindu and Christian communities this area consists of Muslims.
A prominent Kerala mathematician-astronomer Madhava (Madhava) who founded the Kerala school of astronomy and mathematics was from(Irinjalappilly Mana,Aloor) Sangamagrama (Sangamagrama), a town in medieval Kerala believed to be the town of Irinjalakuda. Nagapattinam Chandrashekhara Vasanthakokilam a carnatic singer and actress, was born as Kamakshi in Irinjalakkuda, Cochin State of British India, the present Kerala.
In the 18th century, the ruler of Kingdom of Cochin, Sakthan Thampuran, brought four Christian families for improving commerce and trade to the place known as Chanthappura (in between Nada& Thana) in Irinjalakuda. Economic development took place and Kochi Divan Shanmughan Chetty constructed a canal link known as Shanmugham Canal to Cochin which improved the water transport of goods and hence the business. The canal still exists even it has lost the past glory. The ayurvedic soap, Chandrika, made by C. R. Kesavan Vaidyar originated in Irinjalakuda and was bought by the Bangalore company Wipro. Another company which had made it big is Bombay Stock Exchange listed is Kerala Solvent Extractions Ltd. The company manufacture cattle feed, edible oils and dairy products. KLF Nirmal Industries P Ltd, with their brand KLF Coconad endorsed by Padmasree Mohanlal, is one of the biggest brands in coconut cooking oil.