Muthupet is a panchayat town and taluk in the Thiruvarur district in the Indian state of Tamil Nadu. It is also known as Pearlpet. Muthupet comes under the Thiruthuraipoondi assembly constituency which elects a member to the Tamil Nadu Legislative Assembly every five years. The current member of the legislative assembly (MLA) is Marimuthu of the Communist Party of India, a part of the Nagapattinam (Lok Sabha constituency), which elects its member of parliament (MP) every five years. The Muthupet city in-town panchayat was constituted in 1962. The town comes under the administrative territory of the Thiruvarur District. It extends over an area of 11.80 km².

Muthupet is a panchayat town and taluk in the Tiruvarur District. It is located between Thiruthuraipoondi and Pattukkotai, and around 360 km from Chennai. The town lies adjacent to the Bay of Bengal and is in the southernmost part of the Kaveri Delta. Muthupet is bordered by the Korayar and Bamaniyar rivers to the east and west respectively. The rivers Koriayar and Pamaniyar join near Muthupet, where a lagoon lies that is rich in fish.

Muthupet is a prominent location for fishing, pearl hunting, and bird hunting. Fishing industries are also prominent and produce finfish (koduva), shrimp and crab. A natural mangrove forest, Alayathi Kadu, is one of the largest of its kind in India.

In the early hours of 16 November 2018, Muthupet was heavily affected by Cyclone Gaja. Wind speed reached up to 140-160 kmph in Muthupet, devastating hundreds of huts and thousands of trees. Many houses were destroyed during the cyclone. As a result of over 500 electric poles and over 20 transformers falling down, Muthupet did not regain its power supply until 20 days after Cyclone Gaja struck.

Muthupet mangrove forest is located at the southern end of the Kaveri delta, covering an area of approximately 13,500 ha of which only 4% is occupied by well-grown mangroves. The rivers Paminiyar, Koraiyar, Kilaithankiyar, Marakkakoraiyar and other tributaries of the river Kaveri flow through Muthupet and its adjacent villages. At the tail end, they form the Kaveri Lagoon before meeting the sea.

The northern and western borders of the lagoon are occupied by muddy silt ground which is devoid of mangroves. The mangroves beyond Muthupet Lagoon are discontinuously found along the shore and extend up to Point Calimere. Muthupet mangrove forest was under the control of Chatram Department from 1853 to 1912 (Chengappa, 1918). The government of the presidency of Madras Gazette (1937) shows that, from 1923 to 1936, half of the revenue obtained from selling mangrove products was paid to the revenue department and the remaining half was spent to maintain the "chatrams" (charity homes). The government declared the Muthupet mangrove forest as revenue forest in February 1937 and, accordingly, the mangrove forest was handed over to the forest department of the Madras presidency.

The forest is maintained by the Tamil Nadu Forest Department. The mangrove forest is divided into the Palanjur, Thamarankottai, Maravakkadu, Vadakadu, Thuraikadu and Muthupet reserve forests.

Muthupet reserve forest covers the lagoon, river creeks and the mudflats. Muthupet Lagoon (Mullipallam) is a natural lagoon that is 8 km from nearby Muthupet town and can only be reached by boat. The lagoon is shallow with an average depth of 1 m. The bottom of the lagoon is formed of silt clay substratum. The tidal fluctuations can be observed by the exposure of oyster beds and roots during low tide.