Kottaiyur is the Northern Suburb 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 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.

As of the 2011 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:

1. Ezhil Nagar
2. Sriram Nagar
3. Pari Nagar
4. Udhayam Nagar

And, it comprises the following villages:

1. K. Alagapuri
2. K. Velangudi
3. K. Kallangudi

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

• Alagappa University (Partial) with its second entrance, Alagappa Chettiar statue and memorial arch.
  • Alagappa Institute of Management
  • Alagappa Institute of Physical Education
  • Alagappa Alumni Park
  • Ramanujan Centre for Higher Mathematics.
• Muthuiah Alagappa Matriculation Higher Secondary School.
• Chidambaram Chettiyar Girls Higher Secondary School.
• Thanjavur Arunachalam Chettiyar Government Higher Secondary School.
• Sanatana Dharma Vidyalaya Primary School.
• Kottaiyur Panchayat Union Middle School.

• Dr. Alagappa Chettiar, philanthropist and founder of Alagappa University.
• Roja Muthiah Chettiar
• A. K. Chettiar

• Roja Muthiah in the University of Chicago Magazine