The Thiruvallur district is a district of Tamil Nadu state with its administrative headquarters located at Thiruvallur town. It is believed that the term "Tiruvallur" is derived from the Tamil sentence "tirue vvull?”. The first word "Tiru" means Highness, which is a common prefix for temple towns in South India on the other hand the second word "evvull" means where do I sleep? Thus, both the words together mean a place or town where the god, Veera Raghavar asked a saint for a place to sleep for a night. At present Tiruvallur is well known for the Veeraragava Temple where Amavasya meaning the commencement of dark moon prior to the new moon is considered as an auspicious day for the lord and for the people of the town as well. The Tiruvallur district has been carved out from the earlier Chengalpattu district. After this bifurcation the Tiruvallur revenue division included the sub-taluks of Tiruvallur, Tiruttani taluks and Uthukkottai and Pallipattu which were formerly a part of the Chengalpattu district along with Ponneri and Gummindipoondi taluks of Saidapet revenue division and formed this new district. This region was ruled by the Pallavas for many years. By the end of the 7th century the rule of the Nawab of Arcot was started in this place. The place was also ruled by the Mughals when the Golkonda rulers were defeated in 1687. Finally, the British annexed the Thiruvallur in the beginning of the 19th century. Thiruvallur district came into existence in the year 1999.

Geographically, the district lies at 13°14'N latitude, 79°91'E longitude and 50 m altitude. In the year 2021, there was a total 8.71% forest area of total geographical area. The district encompasses a geographical area of 3,394 sq. km. and it is bounded by Andra Pradesh on the North, Kanchipuram district on the South, Chennai district on the South East, Bay of Bengal on the East and Vellore district on the West. Most of its rainfall occurs in the monsoon season. The actual rainfall in the district was 1729.0 mm in the year of 2021-22.

Administration wise, the district is divided into 12 taluks namely Tiruvottiyur, Madhavaram, Ambattur, Maduravoyal, Avadi, Ponneri, Gummidipoondi, Uthukottai, Tiruvallur, Poonamallee, Tiruttani, and Pallipattu. Moreover, it comprises 58 towns and 617 villages. The administrative language in the district is Tamil.

According to 2011 census the district has a population of 37,28,104 out of which 18,76,062 are males and 18,52,042 are females. The district has a sex ratio of 987 (females for every 1000 males). During the year 2001-2011 the population growth rate in the district was 35.33% including 34.25% were males and 36.45% were females. As per 2011 census the major religion in the district is Hindu with 89.21% of the total population. The population density in the district is 1,098 persons per sq. km. According to 2011 census the principal language in the district is Tamil and Telegu with 83.48% and 11.13%. In the year 2020 the number of live births in the district was 18,790 out of which 9,694 were males and 9,096 were females. In the same year the number of deaths in the district was 17,858 out of which 10,459 were males and 7,399 were females.

The economy of the district is mainly dependent on both the industrial and agricultural activities. The farmers of the district commonly use tanks, tube wells and open wells for the irrigation purpose. The chief agricultural products in the district are Rice, green gram, groundnut, sugarcane, black gram, etc. The adoption of the new agricultural technologies amongst the famers of the district helps to increase the production of various agricultural items. Every year a huge chunk of revenue come from the agricultural products in the district helps in its economy to a great extent. Thiruvallur district is one of the fastest developing districts in the Tamil Nadu state especially in terms of industrial sector. The district is home to many leading industries likewise Madras Refineries, Madras Fertilizers, Manali Petro Chemicals, MRF, Ashok Leyland, TI Cycles, Britannia India Ltd., Parry India Ltd., Hindustan Motors, etc. In the year 2011-12 the gross domestic product in the district was Rs. 42,84,759 lakhs at current price and Rs. 28,03,894 lakhs at constant prices in the year 2004-2005. The net domestic product in the district during the period 2018-19 was Rs. 1,32,12,399 lakh at current price and Rs. 1,00,57,859 lakh at constant prices in the year 2011-2012. The Per Capita Income or NDDP, At Factor Cost during the period 2016-17 was Rs. 2,26,862 at current price and Rs. 1,82,165 at constant prices in the year 2011-2012.

The district is well known as an abode of several reputed educational institutions. It provides a platform for higher education. Some of its recognised educational institutions are Hindu College, Sri Ram Engineering College, Sri Ram Arts and Science College, Victory Institute of Catering & Hotel Management, Bhajarang Engineering College, E.V.P. Engineering College, John Bosco Art and Science College, Dr. Sir Arcot Lakshmana Swami Mudaliar College, etc. As per 2011 census the literacy rate in the district is 84.03% including 89.69% are males and 78.32% are females. The total number of literates in the district is 27,91,721 including 14,95,711 are males and 12,96,010 are females.

Thangavelu Nagarathinam, an eminent Indian politician and a member of the 7th and 11th Lok Sabha from the Sriperumbudur Lok Sabha constituency of Tamil Nadu was born on 1st September, 1933 at Nungambakkam in the Thiruvallur district. He is a vital leader of the Dravida Munnetra Kazhagam (DMK) party.

The district has several centres of attraction which allures many travellers from different parts of the country as well as world. An ancient Shiva temple in a dilapidated condition is the identity of the place, Chembarambakka in the district. Moreover, the walls of the temple are beautifully decorated with some inscriptions of the Chola period. There is also an ancient temple of Lord Varadaraja Perumal with his wife, Pushpakavalli Thayar, located at Poovirundavalli. It is believed that Thirukatchi Nambi Alwar use to do his prayer in this place and moved by his prayer Sri Varadarajaswami, Sri Venkatesaperumal and Sri Ranganathar gave Darshan to him. The temple of Lord Arulmigu Subramaniya Swami temple, located at Tiruttani is one of the significant temples in the Tiruvallur district. It is one of the six temples of Lord Murugan. Pilgrims from far off places come to this temple to offer their prayers. Some other notable places of interest in the district are Poondi Reservoir, Avadi, Vadivudaiamman Temple, Pazhayanur, etc.