Kalutara District (Sinhala: කළුතර දිස්ත්‍රික්කය; Tamil: களுத்துறை மாவட்டம் Kaḷuttuṟai Māvaṭṭam) is one of the 25 districts of Sri Lanka, the second level administrative division of the country. The district is administered by a District Secretariat headed by a District Secretary (previously known as a Government Agent) appointed by the central government of Sri Lanka. The capital of the district is the city of Kalutara .

Kalutara District is located in the south-west of Sri Lanka and has an area of 1,598 square kilometres (617 sq mi). It is bounded by Colombo District in the north, Ratnapura District in the east, Galle District in the south, and the Indian Ocean in the west.

Kalutara District is divided into 14 Divisional Secretary's Division (DS Divisions), each headed by a Divisional Secretary (previously known as an Assistant Government Agent). The DS Divisions are further sub-divided into 762 Grama Niladhari Divisions (GN Divisions).

Kalutara District's population was 1,217,260 in 2012. The majority of the population are Sinhalese, with a minority Sri Lankan Moor and Sri Lankan Tamil population.