Kottaiyur is a Northern Neighborhood of Karaikudi city in Sivaganga district. Formerly, it was a Town panchayat until getting included into Karaikudi City Municipal Corporation. It's the most populous and a well-developed neighborhood or inner-core suburb of Karaikudi. It is known for its Kottaiyur Sivan Temple, one of the master pieces of the Chettinad region. The temple and the area's old lime stone heritage buildings give Kottaiyur a unique identity. Kottaiyur is well developed and famous for its reputed educational institutions. Kottaiyur panchayat administration including the villages of Velangudi and Alagapuri.

The Town got its name from the Chettinad mansions, buildings and palaces which look like forts. In Tamil language, 'Kottai' means 'Fort' and 'Ur' means 'Town'.

Kottaiyur has an average elevation of 77 metres (253 ft) and is located north in Karaikudi, on the Karaikudi-Trichy Highway. It's not on the highway per se, but on one of the routes that joins the highway after Kanadukathan.

As of the 2011^[update] Indian census, Kottaiyur had a population of 14766 of which 49% was male and 51% female. The literacy rate of 75% is higher than the national average of 59.5%. Among men, the literacy rate is 79%, compared to 71% among females. 10% of the population is under six years of age.

Kottaiyur comprises the following Suburban Areas:

And, it comprises the following villages:

Kottaiyur have well reputed schools and colleges around its town. Lot of students from near by surrounding villages and towns are studying here. Following are notable institutions