Ariyalur (Tamil: அரியலூர் மாவட்டம்)is an administrative district in the state of Tamil Nadu in India. The district headquarters are located at Ariyalur. The district occupies an area of 1,949.31 km² and had a population of 752,481 As per the 2011 census.

The Ariyalur district was carved out of Perambalur district on January 1, 2001 during the Dravida Munnetra Kazhagam (DMK) regime. But, it was merged with the Perambalur district by the subsequent All India Anna Dravid Munnetra Kazhagam rule on March 31, 2002 on economic grounds. Ariyalur district reborned on Friday November 23, 2007 and Rural Development and Local Administration Minister M K Stalin will formally inaugurate that 31st district of the State in a function to be held at the ITI playground in Ariyalur.

The district is bordered by the districts of Cuddalore in the north and north-east, Nagapattinam in the east, Thanjavur in the south and south-east, Tiruchirapalli in the south-west and Perambalur in the west. The district has a total of 16 police stations.

Ariyalur (Tamil: அரியலூர்) is a Municipality in Ariyalur district in the state of Tamil Nadu, India. The region near Ariyalur is rich in fossils from the late Maastrichtian. Fossils of the dinosaur Dravidosaurus, dinosaur eggs and numerous other fauna have been recorded here. The fossils in limestone sediment are however threatened as the place is mined for the production of cement by several factories in the region.

Ariyalur is a municipality and headquarters of Ariyalur District in the state of Tamil Nadu. It is rich in limestone resources. Big industrial houses like Birlas (UltraTech Cement), India cements, Dalmia cements, Madras cements have their cement units here. Tamil Nadu government's TANCEM factory is in Ariyalur and is the first factory to establish the cement production in ariyalur and later nearly as far as six more factories have emerged in and around Ariyalur providing employment opportunity to the people.

The Ariyalur Town Panchayat was functioned as Second Grade Town Panchayat from 21.12.1943, then First Grade Town Panchayat from 01.01.1955 and the Selection grade Town Panchayat form 01.04.1966. The extent of Town Panchayat is 7.62 sq kilo meter and strength of Population according to the senses of 2001th year is 27822. In this Town Panchayat there are 18 wards by division, and for which one President and 18 members have been elected by public. Amongst the members, there are 7 women members. As per the Government order 150, dated: 01.10.2004, this Town Panchayat was announced as Special Grade Town Panchayat and then by G.O.No.372 Municipality Administration and Department of supply of Drinking water, dated 16.12.2004, this Town Panchayat has been functioning as Third Grade Municipality from 20.12.2004 and functioning as second grade Municipality from 08.08.2010.