Dhalai is an administrative district in the state of Tripura in India. The district headquarters are located at Ambassa. As of 2011 it is the least populous district of Tripura (out of 8), although it is the largest district in the State.

Dhalai District was created in the year of 1995 by bifurcating North Tripura District and including part of Amarpur Sub-Division of the South Tripura District. It was created keeping in view the administrative exigency of providing development & good governance to the largely Tribal & inaccessible areas. The District is named after Dhalai river which originates in the District.

Located in the North-eastern part of Tripura, the District covers an area of about 2426 km2. It is mainly located between two hills namely ‘Atharamura range’ and ‘Sakhan Range’. More than 70% area is hilly and forest covered. The terrain is mostly undulating and hilly with small water streams (chharas), rivers and fertile valleys intervening. Major rivers originating from Dhalai are Dhalai, Khowai, Gomati & Manu. Major hills are Atharamura, Longtharai, Kalajhari & part of Sakhan. The District headquarter at Ambassa is located at a distance of about 85 km from the State capital Agartala. The District is bordered by Bangladesh on the Northern & Southern sides. Oil and Natural Gas Corporation (ONGC) is currently exploring for natural gas reserves in the district in Salema block. The district falls in Seismic Zone 5 of India and is prone to landslides, thunderstorms and lightning strikes in summer and rainy seasons.

The District has Tropical climate with hot & humid summers, a prolonged rainy season and warm winters. Rains are also frequent in months of March and April. Maximum temperatures in summers & winters are 36 degree & 28 degree Celsius respectively. The minimum temperatures in summers & winters are 17 degree & 5.3 degree Celsius respectively.

According to the 2011 census Dhalai district has a population of 377,988, roughly equal to the nation of Maldives.This gives it a ranking of 564th in India (out of a total of 640).The district has a population density of 157 inhabitants per square kilometre (410/sq mi).Its population growth rate over the decade 2001-2011 was 22.78%.Dhalai has a sex ratio of 945 females for every 1000 males, and a literacy rate of 86.82%.