Kollam or Quilon, an old sea port town on the Arabian coast , stands on the Ashtamudi lake. Kollam , the erstwhile Desinganadu, had a sustained commercial reputation from the days of the Phoenicians and the Romans. Fed by the Chinese trade, it was regarded by Ibn Batuta, as one of the five ports , which he had seen in the course of his travels during a period of twenty four years, in the 14th century.

The rulers of Kollam (Desinganadu) and China , exchange embassies and there was flourishing Chinese settlement at Kollam. Merchant Sulaiman of Siraf in Persia ( 9th Century) found Kollam to be the only port in India , touched by the huge Chinese junks , on his way from Carton of Persian Gulf. Marco Polo, the great Venician traveller, who was in Chinese service under Kublahan in 1275, visited Kollam and other towns on the west coast, in his capacity as a Chinese mandarin.

The Portuguese were the first Europeans to establish a trading center at Kollam in 1502. Then came the Dutch followed by the British in 1795. A British garrison was stationed at Kollam in pursuance of a treaty between Travancore and the British.

Velu Thampi Dalawa of  Travancore, did much for the improvement of the Kollam town. He build new bazaars and invited merchants from Madras and Thirunelveli to settle here. Kollam later became the capital of the enlightened and liberal rulers of Desinganad.

Once a city of palaces, Kollam has been known to the outside world, by the time honoured proverb, "Once you have seen Kollam you would no more need your illam (Home)"

The history of the district as an administrative unit can be traced back to 1835,when the Travancore state consisted of two revenue divisions with headquarters at Kollam and Kottayam. At the time of the integrating of Travancore and Cochin in 1949,Kollam was one of the three revenue divisions in the state. These three revenue divisions were converted into districts. Shencottah taluk was merged with Madras state consequent on the implementation of the state Reorganisation Act of 1956.

When Alappuzha district was formed in 1957, Cherthala, Ambalapuzha, Mavelikkara, Karthikappally. Chenganuur and Thiruvalla Taluks were united to the new district. When Pathanamthitta district was formed on 1st July 1983, the entire Pathanamthitta Taluk and nine villages of Kunnathur Taluk of the district were also removed. Now the district has a single revenue division with headquarters at Kollam. Pathanapuram, Kunnathur, Kottarakkara, Karunagappally and Kollam are the five taluks in the district.