Demography of Karimganj District reveals that the population density of this district is one of the highest in India. According to the last population census held in the year 2001, the average population of Karimganj District is around 10, 07,976. With such density of population (in 2001) and with a total land area of near about 1809 sq. km, the density stands at 557 persons per sq. km. In fact, this is the second highest district level density in the whole of North-east India. With the further growth of population in the last few years, the density has gone up further.

Demographic survey of Karimganj District states that a fairly large percentage of the population belongs to the Scheduled Caste community. It largely comprises Kaibarta and Namashudra castes. Further, the Scheduled Tribe population of Karimganj district is also quite high. The tribal population of this district of Assam largely comprises Dimasa tribe, Khasi tribe, Barmans, Tripuri tribe, Halam tribe and many others. The predominant language of the district is Bengali language (particularly, Sylheti language, a dialect of Bengali spoken by the people of Sylhet, now in Bangladesh, to which Karimganj once belonged). The other important languages spoken in Karimganj district are Hindi language (used largely by the tea-plantation workers who migrated from Bihar, Uttar Pradesh and other states), Manipuri language, Assamese language, Dimasa, Khasi language and so on.

As per the Census report of 2001, in Karimganj district, despite a lot of progress in the field of education in the post-independence period, more than around 45 percent of its population is still illiterate. However, the literacy rate of the district is slightly higher than the average literacy rate of the state. Moreover, the female literacy rate is also comparatively higher in the district. Demography of Karimganj district also suggests that urbanization rate is lower in the district. As much as 93 percent of the district population lives in rural areas. Thus, the ratio of urban population accounts for only around 7 percent as compared to the 11 percent of the state. The rural areas of the district include several semi-urban localities like small townships. These townships have many of the urban facilities, though they are yet to be notified as towns. In Karimganj district there are only two notified urban areas and these are Karimganj (administered by the Karimganj Municipal Board) and Badarpur (administered by Badarpur Town Committee and Badarpur Railway Town Committee). Other semi-urban localities of this district are Ramkrishna Nagar, Patharkandi, Nilambazar etc.