As of the 2011 Census of India, the municipal area of Karimganj city had a population of 56,854, while the wider Karimganj district is home to over 1.2 million people. The city exhibits a steady, albeit moderate, growth rate. The gender ratio in the city is relatively balanced, though it slightly favors males due to the presence of transient trade and labor populations.
The ethnic and cultural composition is predominantly Bengali, heavily influenced by the Sylheti sub-culture. Sylheti—a distinct language or dialect closely related to Bengali—is the primary spoken tongue, while standard Bengali serves as the official language alongside Assamese and English.
Religiously, the city and surrounding region have a mixed demographic, primarily consisting of Hindus and Muslims, with small communities of Christians and Jains. Education levels in the city are robust, boasting a higher literacy rate (over 86% as of 2011) compared to the state average, driven by several historic educational institutions.